Methods, apparatus and systems for uplink transmission of small data

ABSTRACT

Methods for resource efficient data transmission are described herein. A method may comprise operating in one of an idle or an inactive mode and transmitting, in response to a random access (RA) message or a configured grant (CG), a small data transmission over an uplink channel. The RA message may be received in a two-step RA procedure or a four-step RA procedure. The method may further comprise transitioning from the idle or the inactive mode to a connected mode. The method may further comprise determining resources for transmitting the small data transmission. The method may comprise determining whether the small data transmission was successfully received and retransmitting, on a condition the small data transmission was not received, the small data transmission. The method may further comprise segmenting a small data packet into a plurality of small data packets and transmitting the small data packets in a plurality of transmission opportunities.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. PatentApplication Ser. No. 63/007,166, filed Apr. 8, 2020, U.S. PatentApplication Ser. No. 63/061,435, filed Aug. 5, 2020, and U.S. PatentApplication Ser. No. 63/093,996 filed Oct. 20, 2020, the contents ofeach being incorporated by reference as if fully set forth herein.

FIELD

Embodiments disclosed herein generally relate to wireless communicationsand, for example to methods, apparatus and systems for small datatransmission, for example, in the uplink direction.

RELATED ART

Mobile communications using wireless communication continue to evolve. Afifth generation may be referred to as 5G and a sixth generation may bereferred to as 6G. A previous (legacy) generation of mobilecommunication may be, for example, fourth generation (4G) long termevolution (LTE).

SUMMARY

Methods for resource efficient data transmission are described herein. Amethod may comprise operating in one of an idle or an inactive mode andtransmitting, in response to a random access (RA) message or aconfigured grant (CG), a small data transmission over an uplink channel.The RA message may be received in a two-step RA procedure or a four-stepRA procedure. The method may further comprise transitioning from theidle or the inactive mode to a connected mode. The method may furthercomprise determining resources for transmitting the small datatransmission. The method may comprise determining whether the small datatransmission was successfully received and retransmitting, on acondition the small data transmission was not received, the small datatransmission. The method may further comprise segmenting a small datapacket into a plurality of small data packets and transmitting the smalldata packets in a plurality of transmission opportunities.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawings,wherein like reference numerals in the figures indicate like elements,and wherein:

FIG. 1A is a system diagram illustrating an example communicationssystem in which one or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram illustrating an example wirelesstransmit/receive unit (WTRU) that may be used within the communicationssystem illustrated in FIG. 1A according to an embodiment;

FIG. 10 is a system diagram illustrating an example radio access network(RAN) and an example core network (CN) that may be used within thecommunications system illustrated in FIG. 1A according to an embodiment;

FIG. 1D is a system diagram illustrating a further example RAN and afurther example CN that may be used within the communications systemillustrated in FIG. 1A according to an embodiment;

FIG. 2 is a representative procedure that may be implemented by a WTRUto transmit a small data payload using a small data transmission (SDT)resource;

FIG. 3 is a representative procedure that may be implemented by a WTRUto transmit a small data payload using a SDT resource;

FIG. 4 . is a representative procedure that may be implemented by a WTRUusing a SDT resource to determine whether or not to transition toconnected mode;

FIG. 5 is a representative procedure that may be implemented by a WTRUto transmit a small data payload using a SDT resource;

FIG. 6 is a representative procedure that may be implemented by a WTRUusing a SDT resource to determine whether or not to transition toconnected mode;

FIG. 7 is a representative procedure that may be implemented by a basestation to receive a small data payload using a SDT resource from aWTRU;

FIG. 8 is a representative procedure that may be implemented by a basestation to transition a WTRU to connected mode;

FIG. 9 is a representative procedure that may be implemented by a WTRUusing a SDT resource to determine whether or not to transition toconnected mode;

FIG. 10 is a representative procedure that may be implemented by a basestation to transition a WTRU to connected mode;

FIG. 11 is a representative procedure that may be implemented by a WTRUto transmit a small data payload using a contention-free random access(CFRA) resource; and

FIG. 12 is a representative procedure that may be implemented by a basestation to receive a small data payload using a contention-free randomaccess (CFRA) resource.

DETAILED DESCRIPTION

FIG. 1A is a diagram illustrating an example communications system 100in which one or more disclosed embodiments may be implemented. Thecommunications system 100 may be a multiple access system that providescontent, such as voice, data, video, messaging, broadcast, etc., tomultiple wireless users. The communications system 100 may enablemultiple wireless users to access such content through the sharing ofsystem resources, including wireless bandwidth. For example, thecommunications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailunique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S-OFDM),unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bankmulticarrier (FBMC), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network (CN) 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d, any of which maybe referred to as a station (STA), may be configured to transmit and/orreceive wireless signals and may include a user equipment (UE), a mobilestation, a fixed or mobile subscriber unit, a subscription-based unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watchor other wearable, a head-mounted display (HMD), a vehicle, a drone, amedical device and applications (e.g., remote surgery), an industrialdevice and applications (e.g., a robot and/or other wireless devicesoperating in an industrial and/or an automated processing chaincontexts), a consumer electronics device, a device operating oncommercial and/or industrial wireless networks, and the like. Any of theWTRUs 102 a, 102 b, 102 c and 102 d may be interchangeably referred toas a UE.

The communications systems 100 may also include a base station 114 aand/or a base station 114 b. Each of the base stations 114 a, 114 b maybe any type of device configured to wirelessly interface with at leastone of the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to oneor more communication networks, such as the CN 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a NodeB, an eNode B(eNB), a Home Node B, a Home eNode B, a next generation NodeB, such as agNode B (gNB), a new radio (NR) NodeB, a site controller, an accesspoint (AP), a wireless router, and the like. While the base stations 114a, 114 b are each depicted as a single element, it will be appreciatedthat the base stations 114 a, 114 b may include any number ofinterconnected base stations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, and the like. The base station 114 a and/or the base station 114b may be configured to transmit and/or receive wireless signals on oneor more carrier frequencies, which may be referred to as a cell (notshown). These frequencies may be in licensed spectrum, unlicensedspectrum, or a combination of licensed and unlicensed spectrum. A cellmay provide coverage for a wireless service to a specific geographicalarea that may be relatively fixed or that may change over time. The cellmay further be divided into cell sectors. For example, the cellassociated with the base station 114 a may be divided into threesectors. Thus, in one embodiment, the base station 114 a may includethree transceivers, i.e., one for each sector of the cell. In anembodiment, the base station 114 a may employ multiple-input multipleoutput (MIMO) technology and may utilize multiple transceivers for eachsector of the cell. For example, beamforming may be used to transmitand/or receive signals in desired spatial directions.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet(UV), visible light, etc.). The air interface 116 may be establishedusing any suitable radio access technology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed Downlink(DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet Access(HSUPA).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as Evolved UMTS TerrestrialRadio Access (E-UTRA), which may establish the air interface 116 usingLong Term Evolution (LTE) and/or LTE-Advanced (LTE-A) and/orLTE-Advanced Pro (LTE-A Pro).

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement a radio technology such as NR Radio Access, which mayestablish the air interface 116 using NR.

In an embodiment, the base station 114 a and the WTRUs 102 a, 102 b, 102c may implement multiple radio access technologies. For example, thebase station 114 a and the WTRUs 102 a, 102 b, 102 c may implement LTEradio access and NR radio access together, for instance using dualconnectivity (DC) principles. Thus, the air interface utilized by WTRUs102 a, 102 b, 102 c may be characterized by multiple types of radioaccess technologies and/or transmissions sent to/from multiple types ofbase stations (e.g., an eNB and a gNB).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.11 (i.e.,Wireless Fidelity (WiFi), IEEE 802.16 (i.e., Worldwide Interoperabilityfor Microwave Access (WiMAX)), CDMA2000, CDMA2000 1×, CDMA2000 EV-DO,Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), Global System for Mobile communications (GSM),Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and thelike.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, an industrialfacility, an air corridor (e.g., for use by drones), a roadway, and thelike. In one embodiment, the base station 114 b and the WTRUs 102 c, 102d may implement a radio technology such as IEEE 802.11 to establish awireless local area network (WLAN). In an embodiment, the base station114 b and the WTRUs 102 c, 102 d may implement a radio technology suchas IEEE 802.15 to establish a wireless personal area network (WPAN). Inyet another embodiment, the base station 114 b and the WTRUs 102 c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, LTE-A Pro, NR etc.) to establish a picocell or femtocell. Asshown in FIG. 1A, the base station 114 b may have a direct connection tothe Internet 110. Thus, the base station 114 b may not be required toaccess the Internet 110 via the CN 106.

The RAN 104 may be in communication with the CN 106, which may be anytype of network configured to provide voice, data, applications, and/orvoice over internet protocol (VoIP) services to one or more of the WTRUs102 a, 102 b, 102 c, 102 d. The data may have varying quality of service(QoS) requirements, such as differing throughput requirements, latencyrequirements, error tolerance requirements, reliability requirements,data throughput requirements, mobility requirements, and the like. TheCN 106 may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the CN 106 may be in direct or indirectcommunication with other RANs that employ the same RAT as the RAN 104 ora different RAT. For example, in addition to being connected to the RAN104, which may be utilizing a NR radio technology, the CN 106 may alsobe in communication with another RAN (not shown) employing a GSM, UMTS,CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

The CN 106 may also serve as a gateway for the WTRUs 102 a, 102 b, 102c, 102 d to access the PSTN 108, the Internet 110, and/or the othernetworks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) and/orthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired and/or wireless communications networksowned and/or operated by other service providers. For example, thenetworks 112 may include another CN connected to one or more RANs, whichmay employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities (e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks). For example, the WTRU 102 c shown in FIG. 1A may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram illustrating an example WTRU 102. As shownin FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120,a transmit/receive element 122, a speaker/microphone 124, a keypad 126,a display/touchpad 128, non-removable memory 130, removable memory 132,a power source 134, a global positioning system (GPS) chipset 136,and/or other peripherals 138, among others. It will be appreciated thatthe WTRU 102 may include any sub-combination of the foregoing elementswhile remaining consistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), anyother type of integrated circuit (IC), a state machine, and the like.The processor 118 may perform signal coding, data processing, powercontrol, input/output processing, and/or any other functionality thatenables the WTRU 102 to operate in a wireless environment. The processor118 may be coupled to the transceiver 120, which may be coupled to thetransmit/receive element 122. While FIG. 1B depicts the processor 118and the transceiver 120 as separate components, it will be appreciatedthat the processor 118 and the transceiver 120 may be integratedtogether in an electronic package or chip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In an embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and/or receive both RF and light signals. It will beappreciated that the transmit/receive element 122 may be configured totransmit and/or receive any combination of wireless signals.

Although the transmit/receive element 122 is depicted in FIG. 1B as asingle element, the WTRU 102 may include any number of transmit/receiveelements 122. More specifically, the WTRU 102 may employ MIMOtechnology. Thus, in one embodiment, the WTRU 102 may include two ormore transmit/receive elements 122 (e.g., multiple antennas) fortransmitting and receiving wireless signals over the air interface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as NR and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs and/or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, a Virtual Reality and/or Augmented Reality (VR/AR) device, anactivity tracker, and the like. The peripherals 138 may include one ormore sensors. The sensors may be one or more of a gyroscope, anaccelerometer, a hall effect sensor, a magnetometer, an orientationsensor, a proximity sensor, a temperature sensor, a time sensor; ageolocation sensor, an altimeter, a light sensor, a touch sensor, amagnetometer, a barometer, a gesture sensor, a biometric sensor, ahumidity sensor and the like.

The WTRU 102 may include a full duplex radio for which transmission andreception of some or all of the signals (e.g., associated withparticular subframes for both the UL (e.g., for transmission) and DL(e.g., for reception) may be concurrent and/or simultaneous. The fullduplex radio may include an interference management unit to reduce andor substantially eliminate self-interference via either hardware (e.g.,a choke) or signal processing via a processor (e.g., a separateprocessor (not shown) or via processor 118). In an embodiment, the WTRU102 may include a half-duplex radio for which transmission and receptionof some or all of the signals (e.g., associated with particularsubframes for either the UL (e.g., for transmission) or the DL (e.g.,for reception)).

FIG. 10 is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the CN 106.

The RAN 104 may include eNode-Bs 160 a, 160 b, 160 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 160 a, 160 b, 160c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 160 a, 160 b, 160 c may implement MIMO technology. Thus,the eNode-B 160 a, for example, may use multiple antennas to transmitwireless signals to, and/or receive wireless signals from, the WTRU 102a.

Each of the eNode-Bs 160 a, 160 b, 160 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the UL and/or DL, and the like. As shown in FIG. 10 , the eNode-Bs160 a, 160 b, 160 c may communicate with one another over an X2interface.

The CN 106 shown in FIG. 10 may include a mobility management entity(MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN)gateway (PGW) 166. While the foregoing elements are depicted as part ofthe CN 106, it will be appreciated that any of these elements may beowned and/or operated by an entity other than the CN operator.

The MME 162 may be connected to each of the eNode-Bs 162 a, 162 b, 162 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 162 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 162 may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM and/or WCDMA.

The SGW 164 may be connected to each of the eNode Bs 160 a, 160 b, 160 cin the RAN 104 via the S1 interface. The SGW 164 may generally route andforward user data packets to/from the WTRUs 102 a, 102 b, 102 c. The SGW164 may perform other functions, such as anchoring user planes duringinter-eNode B handovers, triggering paging when DL data is available forthe WTRUs 102 a, 102 b, 102 c, managing and storing contexts of theWTRUs 102 a, 102 b, 102 c, and the like.

The SGW 164 may be connected to the PGW 166, which may provide the WTRUs102 a, 102 b, 102 c with access to packet-switched networks, such as theInternet 110, to facilitate communications between the WTRUs 102 a, 102b, 102 c and IP-enabled devices.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may provide the WTRUs 102 a, 102 b, 102 c withaccess to circuit-switched networks, such as the PSTN 108, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and traditionalland-line communications devices. For example, the CN 106 may include,or may communicate with, an IP gateway (e.g., an IP multimedia subsystem(IMS) server) that serves as an interface between the CN 106 and thePSTN 108. In addition, the CN 106 may provide the WTRUs 102 a, 102 b,102 c with access to the other networks 112, which may include otherwired and/or wireless networks that are owned and/or operated by otherservice providers.

Although the WTRU is described in FIGS. 1A-1D as a wireless terminal, itis contemplated that in certain representative embodiments that such aterminal may use (e.g., temporarily or permanently) wired communicationinterfaces with the communication network.

In representative embodiments, the other network 112 may be a WLAN.

A WLAN in Infrastructure Basic Service Set (BSS) mode may have an AccessPoint (AP) for the BSS and one or more stations (STAs) associated withthe AP. The AP may have access or an interface to a Distribution System(DS) or another type of wired/wireless network that carries traffic into and/or out of the BSS. Traffic to STAs that originates from outsidethe BSS may arrive through the AP and may be delivered to the STAs.Traffic originating from STAs to destinations outside the BSS may besent to the AP to be delivered to respective destinations. Trafficbetween STAs within the BSS may be sent through the AP, for example,where the source STA may send traffic to the AP and the AP may deliverthe traffic to the destination STA. The traffic between STAs within aBSS may be considered and/or referred to as peer-to-peer traffic. Thepeer-to-peer traffic may be sent between (e.g., directly between) thesource and destination STAs with a direct link setup (DLS). In certainrepresentative embodiments, the DLS may use an 802.11e DLS or an 802.11ztunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may nothave an AP, and the STAs (e.g., all of the STAs) within or using theIBSS may communicate directly with each other. The IBSS mode ofcommunication may sometimes be referred to herein as an “ad-hoc” mode ofcommunication.

When using the 802.11ac infrastructure mode of operation or a similarmode of operations, the AP may transmit a beacon on a fixed channel,such as a primary channel. The primary channel may be a fixed width(e.g., 20 MHz wide bandwidth) or a dynamically set width. The primarychannel may be the operating channel of the BSS and may be used by theSTAs to establish a connection with the AP. In certain representativeembodiments, Carrier Sense Multiple Access with Collision Avoidance(CSMA/CA) may be implemented, for example in 802.11 systems. ForCSMA/CA, the STAs (e.g., every STA), including the AP, may sense theprimary channel. If the primary channel is sensed/detected and/ordetermined to be busy by a particular STA, the particular STA may backoff. One STA (e.g., only one station) may transmit at any given time ina given BSS.

High Throughput (HT) STAs may use a 40 MHz wide channel forcommunication, for example, via a combination of the primary 20 MHzchannel with an adjacent or nonadjacent 20 MHz channel to form a 40 MHzwide channel.

Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz, 80 MHz,and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz, channels may beformed by combining contiguous 20 MHz channels. A 160 MHz channel may beformed by combining 8 contiguous 20 MHz channels, or by combining twonon-contiguous 80 MHz channels, which may be referred to as an 80+80configuration. For the 80+80 configuration, the data, after channelencoding, may be passed through a segment parser that may divide thedata into two streams. Inverse Fast Fourier Transform (IFFT) processing,and time domain processing, may be done on each stream separately. Thestreams may be mapped on to the two 80 MHz channels, and the data may betransmitted by a transmitting STA. At the receiver of the receiving STA,the above described operation for the 80+80 configuration may bereversed, and the combined data may be sent to the Medium Access Control(MAC).

Sub 1 GHz modes of operation are supported by 802.11af and 802.11ah. Thechannel operating bandwidths, and carriers, are reduced in 802.11af and802.11ah relative to those used in 802.11n, and 802.11ac. 802.11afsupports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space(TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and16 MHz bandwidths using non-TVWS spectrum. According to a representativeembodiment, 802.11ah may support Meter Type Control/Machine-TypeCommunications (MTC), such as MTC devices in a macro coverage area. MTCdevices may have certain capabilities, for example, limited capabilitiesincluding support for (e.g., only support for) certain and/or limitedbandwidths. The MTC devices may include a battery with a battery lifeabove a threshold (e.g., to maintain a very long battery life).

WLAN systems, which may support multiple channels, and channelbandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include achannel which may be designated as the primary channel. The primarychannel may have a bandwidth equal to the largest common operatingbandwidth supported by all STAs in the BSS. The bandwidth of the primarychannel may be set and/or limited by a STA, from among all STAs inoperating in a BSS, which supports the smallest bandwidth operatingmode. In the example of 802.11ah, the primary channel may be 1 MHz widefor STAs (e.g., MTC type devices) that support (e.g., only support) a 1MHz mode, even if the AP, and other STAs in the BSS support 2 MHz, 4MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.Carrier sensing and/or Network Allocation Vector (NAV) settings maydepend on the status of the primary channel. If the primary channel isbusy, for example, due to a STA (which supports only a 1 MHz operatingmode) transmitting to the AP, all available frequency bands may beconsidered busy even though a majority of the available frequency bandsremains idle.

In the United States, the available frequency bands, which may be usedby 802.11ah, are from 902 MHz to 928 MHz. In Korea, the availablefrequency bands are from 917.5 MHz to 923.5 MHz. In Japan, the availablefrequency bands are from 916.5 MHz to 927.5 MHz. The total bandwidthavailable for 802.11ah is 6 MHz to 26 MHz depending on the country code.

FIG. 1D is a system diagram illustrating the RAN 104 and the CN 106according to an embodiment. As noted above, the RAN 104 may employ an NRradio technology to communicate with the WTRUs 102 a, 102 b, 102 c overthe air interface 116. The RAN 104 may also be in communication with theCN 106.

The RAN 104 may include gNBs 180 a, 180 b, 180 c, though it will beappreciated that the RAN 104 may include any number of gNBs whileremaining consistent with an embodiment. The gNBs 180 a, 180 b, 180 cmay each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the gNBs 180 a, 180 b, 180 c may implement MIMO technology. For example,gNBs 180 a, 108 b may utilize beamforming to transmit signals to and/orreceive signals from the gNBs 180 a, 180 b, 180 c. Thus, the gNB 180 a,for example, may use multiple antennas to transmit wireless signals to,and/or receive wireless signals from, the WTRU 102 a. In an embodiment,the gNBs 180 a, 180 b, 180 c may implement carrier aggregationtechnology. For example, the gNB 180 a may transmit multiple componentcarriers to the WTRU 102 a (not shown). A subset of these componentcarriers may be on unlicensed spectrum while the remaining componentcarriers may be on licensed spectrum. In an embodiment, the gNBs 180 a,180 b, 180 c may implement Coordinated Multi-Point (CoMP) technology.For example, WTRU 102 a may receive coordinated transmissions from gNB180 a and gNB 180 b (and/or gNB 180 c).

The WTRUs 102 a, 102 b, 102 c may communicate with gNBs 180 a, 180 b,180 c using transmissions associated with a scalable numerology. Forexample, the OFDM symbol spacing and/or OFDM subcarrier spacing may varyfor different transmissions, different cells, and/or different portionsof the wireless transmission spectrum. The WTRUs 102 a, 102 b, 102 c maycommunicate with gNBs 180 a, 180 b, 180 c using subframe or transmissiontime intervals (TTIs) of various or scalable lengths (e.g., containing avarying number of OFDM symbols and/or lasting varying lengths ofabsolute time).

The gNBs 180 a, 180 b, 180 c may be configured to communicate with theWTRUs 102 a, 102 b, 102 c in a standalone configuration and/or anon-standalone configuration. In the standalone configuration, WTRUs 102a, 102 b, 102 c may communicate with gNBs 180 a, 180 b, 180 c withoutalso accessing other RANs (e.g., such as eNode-Bs 160 a, 160 b, 160 c).In the standalone configuration, WTRUs 102 a, 102 b, 102 c may utilizeone or more of gNBs 180 a, 180 b, 180 c as a mobility anchor point. Inthe standalone configuration, WTRUs 102 a, 102 b, 102 c may communicatewith gNBs 180 a, 180 b, 180 c using signals in an unlicensed band. In anon-standalone configuration WTRUs 102 a, 102 b, 102 c may communicatewith/connect to gNBs 180 a, 180 b, 180 c while also communicatingwith/connecting to another RAN such as eNode-Bs 160 a, 160 b, 160 c. Forexample, WTRUs 102 a, 102 b, 102 c may implement DC principles tocommunicate with one or more gNBs 180 a, 180 b, 180 c and one or moreeNode-Bs 160 a, 160 b, 160 c substantially simultaneously. In thenon-standalone configuration, eNode-Bs 160 a, 160 b, 160 c may serve asa mobility anchor for WTRUs 102 a, 102 b, 102 c and gNBs 180 a, 180 b,180 c may provide additional coverage and/or throughput for servicingWTRUs 102 a, 102 b, 102 c.

Each of the gNBs 180 a, 180 b, 180 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, scheduling of users in the ULand/or DL, support of network slicing, DC, interworking between NR andE-UTRA, routing of user plane data towards User Plane Function (UPF) 184a, 184 b, routing of control plane information towards Access andMobility Management Function (AMF) 182 a, 182 b and the like. As shownin FIG. 1D, the gNBs 180 a, 180 b, 180 c may communicate with oneanother over an Xn interface.

The CN 106 shown in FIG. 1D may include at least one AMF 182 a, 182 b,at least one UPF 184 a, 184 b, at least one Session Management Function(SMF) 183 a, 183 b, and possibly a Data Network (DN) 185 a, 185 b. Whilethe foregoing elements are depicted as part of the CN 106, it will beappreciated that any of these elements may be owned and/or operated byan entity other than the CN operator.

The AMF 182 a, 182 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 104 via an N2 interface and may serve as acontrol node. For example, the AMF 182 a, 182 b may be responsible forauthenticating users of the WTRUs 102 a, 102 b, 102 c, support fornetwork slicing (e.g., handling of different protocol data unit (PDU)sessions with different requirements), selecting a particular SMF 183 a,183 b, management of the registration area, termination of non-accessstratum (NAS) signaling, mobility management, and the like. Networkslicing may be used by the AMF 182 a, 182 b in order to customize CNsupport for WTRUs 102 a, 102 b, 102 c based on the types of servicesbeing utilized WTRUs 102 a, 102 b, 102 c. For example, different networkslices may be established for different use cases such as servicesrelying on ultra-reliable low latency (URLLC) access, services relyingon enhanced massive mobile broadband (eMBB) access, services for MTCaccess, and the like. The AMF 182 a, 182 b may provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro,and/or non-3GPP access technologies such as WiFi.

The SMF 183 a, 183 b may be connected to an AMF 182 a, 182 b in the CN106 via an N11 interface. The SMF 183 a, 183 b may also be connected toa UPF 184 a, 184 b in the CN 106 via an N4 interface. The SMF 183 a, 183b may select and control the UPF 184 a, 184 b and configure the routingof traffic through the UPF 184 a, 184 b. The SMF 183 a, 183 b mayperform other functions, such as managing and allocating WTRU IPaddress, managing PDU sessions, controlling policy enforcement and QoS,providing DL data notifications, and the like. A PDU session type may beIP-based, non-IP based, Ethernet-based, and the like.

The UPF 184 a, 184 b may be connected to one or more of the gNBs 180 a,180 b, 180 c in the RAN 104 via an N3 interface, which may provide theWTRUs 102 a, 102 b, 102 c with access to packet-switched networks, suchas the Internet 110, to facilitate communications between the WTRUs 102a, 102 b, 102 c and IP-enabled devices. The UPF 184, 184 b may performother functions, such as routing and forwarding packets, enforcing userplane policies, supporting multi-homed PDU sessions, handling user planeQoS, buffering DL packets, providing mobility anchoring, and the like.

The CN 106 may facilitate communications with other networks. Forexample, the CN 106 may include, or may communicate with, an IP gateway(e.g., an IP multimedia subsystem (IMS) server) that serves as aninterface between the CN 106 and the PSTN 108. In addition, the CN 106may provide the WTRUs 102 a, 102 b, 102 c with access to the othernetworks 112, which may include other wired and/or wireless networksthat are owned and/or operated by other service providers. In oneembodiment, the WTRUs 102 a, 102 b, 102 c may be connected to a local DN185 a, 185 b through the UPF 184 a, 184 b via the N3 interface to theUPF 184 a, 184 b and an N6 interface between the UPF 184 a, 184 b andthe DN 185 a, 185 b.

In view of FIGS. 1A-1D, and the corresponding description of FIGS.1A-1D, one or more, or all, of the functions described herein withregard to one or more of: WTRU 102 a-d, Base Station 114 a-b, eNode-B160 a-c, MME 162, SGW 164, PGW 166, gNB 180 a-c, AMF 182 a-b, UPF 184a-b, SMF 183 a-b, DN 185 a-b, and/or any other device(s) describedherein, may be performed by one or more emulation devices (not shown).The emulation devices may be one or more devices configured to emulateone or more, or all, of the functions described herein. For example, theemulation devices may be used to test other devices and/or to simulatenetwork and/or WTRU functions.

The emulation devices may be designed to implement one or more tests ofother devices in a lab environment and/or in an operator networkenvironment. For example, the one or more emulation devices may performthe one or more, or all, functions while being fully or partiallyimplemented and/or deployed as part of a wired and/or wirelesscommunication network in order to test other devices within thecommunication network. The one or more emulation devices may perform theone or more, or all, functions while being temporarilyimplemented/deployed as part of a wired and/or wireless communicationnetwork. The emulation device may be directly coupled to another devicefor purposes of testing and/or performing testing using over-the-airwireless communications.

The one or more emulation devices may perform the one or more, includingall, functions while not being implemented/deployed as part of a wiredand/or wireless communication network. For example, the emulationdevices may be utilized in a testing scenario in a testing laboratoryand/or a non-deployed (e.g., testing) wired and/or wirelesscommunication network in order to implement testing of one or morecomponents. The one or more emulation devices may be test equipment.Direct RF coupling and/or wireless communications via RF circuitry(e.g., which may include one or more antennas) may be used by theemulation devices to transmit and/or receive data.

The following abbreviations may be used throughout this disclosure.

CG Configured grant or cell groupDG Dynamic grantCAPC Channel access priority classDFI Downlink feedback information

HARQ PID HARQ Process ID

eLAA enhanced Licensed Assisted AccessFeLAA Further enhanced Licensed Assisted AccessMAC CE MAC control elementRO RACH occasionRA random access

PRACH Physical Random-access Channel ACK Acknowledgement BLER BlockError Rate BWP Bandwidth Part CAP Channel Access Priority CCA ClearChannel Assessment CP Cyclic Prefix

CP-OFDM Conventional OFDM (relying on cyclic prefix)

CQI Channel Quality Indicator CRC Cyclic Redundancy Check CSI ChannelState Information CW Contention Window CWS Contention Window Size COChannel Occupancy DAI Downlink Assignment Index DCI Downlink ControlInformation DL Downlink DM-RS Demodulation Reference Signal DRB DataRadio Bearer HARQ Hybrid Automatic Repeat Request LAA License AssistedAccess LBT Listen-Before-Talk

LTE Long Term Evolution e.g. from 3GPP LTE R8 and up

NACK Negative ACK MCS Modulation and Coding Scheme MIMO Multiple InputMultiple Output NR New Radio OFDM Orthogonal Frequency-DivisionMultiplexing PHY Physical Layer PRACH Physical Random Access Channel PSSPrimary Synchronization Signal

RACH Random Access Channel (or procedure)

RAR Random Access Response

RCU Radio access network Central Unit

RF Radio Front end RLF Radio Link Failure RLM Radio Link Monitoring RNTIRadio Network Identifier RRC Radio Resource Control RRM Radio ResourceManagement RS Reference Signal RSRP Reference Signal Received Power RSSIReceived Signal Strength Indicator SDU Service Data Unit SRS SoundingReference Signal SS Synchronization Signal SSS Secondary SynchronizationSignal

SWG Switching Gap (in a self-contained subframe)SPS Semi-persistent scheduling

SUL Supplemental Uplink TB Transport Block TBS Transport Block Size TRPTransmission/Reception Point

TSC Time-sensitive communicationsTSN Time-sensitive networking

UL Uplink URLLC Ultra-Reliable and Low Latency Communications WBWP WideBandwidth Part

WLAN Wireless Local Area Networks and related technologies (IEEE 802.xxdomain)

The following terminology may be used throughout this disclosure. “CSI”may refer to channel state information, which may include at least oneof the following: a channel quality index (CQI); a rank indicator (RI);a precoding matrix index (PMI); an L1 channel measurement (e.g. areference signal received power (RSRP) such as L1-RSRP, orsignal-to-interference-plus-noise ratio (SINR); a CSI-RS resourceindicator (CRI); a synchronization signal/physical broadcast channel(SS/PBCH) block resource indicator (SSBRI); a layer indicator (LI);and/or any other measurement quantity measured by the WTRU from theconfigured CSI-RS or SS/PBCH block.

“UCI” may refer to uplink control information, which may include: CSI;HARQ feedback for one or more HARQ processes; a scheduling request (SR);a link recovery request (LRR); a CG-UCI and/or other control informationbits that may be transmitted on the physical uplink control channel(PUCCH) or physical uplink shared channel (PUSCH).

“Channel conditions” may refer to any conditions relating to the stateof the radio/channel, which may be determined by the WTRU from: a WTRUmeasurement (e.g., L1/SINR/RSRP, CQI/MCS, channel occupancy, RSSI, powerheadroom, exposure headroom); L3/mobility-based measurements (e.g. RSRP,RSRQ); a radio link monitoring (RLM) state; and/or channel availabilityin an unlicensed spectrum (e.g. whether the channel is occupied based ondetermination of a listen-before-talk (LBT) procedure or whether thechannel is deemed to have experienced a consistent LBT failure).

“Physical random access channel (PRACH) resource” may refer to a PRACHresource (e.g., in frequency), a PRACH occasion (RO) (e.g., in time); apreamble format (e.g., in terms of total preamble duration, sequencelength, guard time duration and/or in terms of length of cyclic prefix);and/or a certain preamble sequence used for the transmission of apreamble in a random access procedure.

“Small data” may refer to uplink-shared channel (UL-SCH) data(non-control channel) transmitted by the WTRU in a non-connected mode.

“MsgA” may refer to preamble and payload transmissions on PRACH andPUSCH resources respectively in a two-step RA procedure, as defined, forexample, in 3GPP Technical Specification (TS) 38.321.

“MsgB” may refer to the downlink response to MsgA, which may be a RARindicating successful access, a fallback RAR, or a backoff indication,as defined, for example, in 3GPP TS 38.321.

A wireless transmit/receive unit (WTRU) may operate in a variety oftransmission and reception modes including inactive, idle, and connectedmodes. When a WTRU transitions from an inactive mode into a connectedmode to send a small amount of data, this may result in increasedsignaling overhead in the network and increased battery consumption. Fordevices supporting enhanced mobile broadband (eMBB) services,applications may perform frequent background small data transmissions,for example, to refresh app data or provide notifications, which may beperiodic or aperiodic. Further, sensors and Internet of Things (IoT)devices may have a considerable amount of signaling and small data, forexample, periodic heartbeat or stay-alive signals, surveillance updates,periodic video stream, and non-periodic video based on motion sensing.Requiring the WTRU to move to connected mode for such small data orsignaling may affect power consumption considerably, especially forpower or battery limited sensor/IoT devices or for eMBB mobile devicesaiming to reduce battery consumption.

In two-step random access (RA) procedures and configured grantssupported in Third Generation Partnership Project (3GPP) standards forNew Radio (NR), uplink (UL) and downlink (DL) small data transmissionsmay be enabled without necessarily transitioning to connected mode.Solutions in NR Release 17 may be scoped for data transmission withoutWTRU-initiated state transitions for both UL and DL. For example, it maybe desirable not to introduce new RRC states, and it may be advantageousthat the network retain control over transmissions of small data in UL,subsequent transmissions of small data in UL and DL, and statetransition decisions. Solutions in NR Release 17 may be scoped usingtwo-step RA procedures, four-step RA procedures, and configured grant(CG) transmission in inactive mode. The WTRU context in inactive modemay include the configuration of radio bearers, logical channels andsecurity information. The WTRU may keep all or a part of its context ininactive and/or idle mode. Some dedicated radio bearers (DRBs) may besuspended in inactive or idle mode.

A property of scheduling information (e.g., an uplink grant or adownlink assignment) may consist of at least one of the following: afrequency allocation; an aspect of time allocation, such as a duration;a priority; a modulation and coding scheme; a transport block size; anumber of spatial layers; a number of transport blocks to be carried; aTCI state or SRI; a number of repetitions; or whether the grant is aconfigured grant type 1, type 2, or a dynamic grant.

An indication by DCI may comprise at least one of an explicit indicationby a DCI field or by RNTI used to mask CRC of the PDCCH. An indicationby the DCI may also be an implicit indication by a property such as: aDCI format; a DCI size; a control resources set (CORESET) or searchspace; an aggregation level; an identity of a first control channelresource (e.g., an index of a first control channel element (CCE)) for aDCI, where the mapping between the property and the value may besignaled by RRC or MAC.

Small uplink data transfers may raise various problems with respect toresource allocation and power. For example, a transition of the controlplane connectivity state from either the idle mode or the inactive modeinto connected mode to send or receive a small amount of user plane datafor a dedicated radio bearer (a DRB, or a SRB) may lead to increasedsignaling overhead in the network and increased battery consumption forthe WTRU.

It may be advantageous for a WTRU to be able to transmit variableamounts of small data in the uplink without having to transition into adifferent connectivity state or into a different power usage or powersaving mode. In NR Release 15 and Release 16 standards, for instance,transmission of user plane data for a dedicated radio bearer (e.g., DRB,SRB) while not in the RRC connected mode is not supported. Thus, methodsto support uplink data transmission in idle or inactive modes may bedesirable to enable uplink transmissions of small amounts of unicastdata.

In some solutions, a WTRU may perform resource selection and transmittransport blocks (TBs) of variable sizes. The WTRU may transmit smalldata, optionally supported by a preamble transmission during a two-stepand/or four-step random access channel (RACH) procedure, for example,via one or more of the following methods described herein. In subsequentsections, such transmission of TBs may be referred to as a transmissionopportunity.

In the context of a four-step RACH procedure, an UL grant may beprovided in Msg2. For example, the Msg2 response message may include anUL grant for transmission of subsequent small data (e.g. while the WTRUremains in an inactive state).

In some solutions, the small data may be transmitted as part of a as aMsg3 PUSCH resource.

In some solutions, an UL grant may be provided in Msg4 of a four-stepRACH procedure. For example, the Msg4 response message may include an ULgrant for transmission of subsequent small data (e.g. while the WTRUremains in RRC INACTIVE state). The WTRU may possibly indicateadditional information about the small data payload in Msg3 (and/orpossibly msgA) e.g. transport block size, QoS characteristics such aslatency and/or reliability requirements. In some embodiments an UL grantmay be accompanied with an applicable HARQ process ID indicated usingpart of the scheduling information.

In some solutions, such as in a two-step RACH procedure, the WTRU maytransmit small data as a MsgA PUSCH resource.

An UL grant may be provided in MsgB. The MsgB response message mayinclude UL grant for transmission of subsequent small data (e.g. whilethe WTRU remains in an inactive state). The WTRU may possibly indicateadditional information about the small data payload in MsgA (and/orpossibly Msg3) such as transport block size, QoS characteristics such aslatency or reliability requirements. In some embodiments, an UL grantmay be accompanied with an applicable HARQ process ID indicated in partof the scheduling information.

The WTRU may select one or more transmission opportunities for smalldata transmission via selection of a linked resource. For example, theWTRU may select one or more RACH preambles and/or RACH occasionsassociated with a small data transmission opportunity or opportunities.The RACH preambles and or RACH occasions may be shared between smalldata transmission and legacy random access, exclusively used for legacyrandom access, or exclusively used for small data transmission. Thepreamble and or RACH occasion selection may also be subject torestrictions and/or small data characteristics (e.g. a validity criteriadescribed in subsequent sections).

Resource selection-to-transmission opportunity links may be configureddynamically or semi-statically. The WTRU may obtain the association ofresources with small data transmission opportunities in, for instance,one or more of the following methods. In some cases, the WTRU may obtainthe association via dedicated signaling, such as via RRC or MAC controlelements. In some cases, the WTRU may obtain the association throughbroadcast signaling, such as via system information.

In some solutions, a WTRU may select and optionally validate a resourcefor a small data transmission. For example, the WTRU may select aresource linked with a first available small data transmissionopportunity. In another possible solution, the WTRU may only selectresources linked to a transmission opportunity that satisfy one or morecriteria. For instance, a transmission opportunity and linked resourcemay be subject to one or more conditions.

As one condition, a WTRU may or may not select a specific transmissionopportunity or linked resource based on one or more WTRU capabilities.For example, the WTRU may not be capable of performing a two-step RACH,and thus small data transmissions to be performed in transmissionopportunities associated with MsgA and/or MsgB may not be allowed. Inanother example, the WTRU may only be capable of supporting small datatransmission within a certain bit size. In another example, the WTRU maybe subject to minimum processing requirements.

As another condition, a WTRU may or may not select a specifictransmission opportunity or linked resource based on the characteristicsof the data packet intended for that transmission opportunity. Forexample, the transmission opportunity may only support a maximum smalldata packet size and/or range of allowable packet sizes. In some cases,the small data may be subject to QoS requirements such as, for example,latency and reliability requirements. In some cases, the condition maybe based on the type of data (e.g. MAC CE, small data) and associatedpriority. For instance, the WTRU may select a given resource only if itmeets the QoS requirements associated with the buffered small data. Inanother example, a WTRU may be configured with the type of MAC CEs thatcan be included in resources applicable for small data transfer.

As another condition, a WTRU may or may not select a specifictransmission opportunity or linked resource based on the channelconditions. For example, a WTRU may not select a specific resource ifthe channel conditions (e.g. RSRP/RSRQ/SINR) fall below a specific orconfigured (e.g., preconfigured) threshold.

As another condition, a WTRU may or may not select a specifictransmission opportunity or linked resource based on the WTRU'ssynchronization status with the network. For example, the WTRU may needto maintain a timing synchronization requirement in order to transmit ona transmission opportunity.

As another condition, a WTRU may or may not select a specifictransmission opportunity or linked resource based on the mobility statusof the WTRU. For example, a WTRU may transmit in a small datatransmission opportunity if it is stationary or in a low mobilitystatus. In another example, the WTRU may select a subset of PRACH and/orPUSCH resources in the target cell for small data transfer duringhandover.

As another condition, a WTRU may or may not select a specifictransmission opportunity/linked resource based on the position of theWTRU within the cell. The position may be determined, for example, basedon one or more of an RSRP/RSRQ, GPS methods, or network-based positionmethods. For example, the WTRU may be allowed to transmit on a smalldata opportunity or select a linked resource if it is, for instance,within the cell center, at some position relative to a cell edge, or ata specific distance range.

As another condition, a WTRU may or may not select a specifictransmission opportunity or linked resource based on the Random Accesstype. The type may be, for example, RA for mobility, BFR, or initialaccess. As another condition, a WTRU may or may not select a specifictransmission opportunity/linked resource based on whether a packet issegment of a larger packet or whether the packet comprises a singlesmall data packet.

In some solutions, the WTRU MAC may perform a single RA procedure at atime. The WTRU may have more than one RA procedure triggered fordifferent RA types or triggers, such as small data transfer, mobility,beam failure recovery, or system information acquisition. In casemultiple RA procedures are triggered, the WTRU may initiate a single RAprocedure for one of the RA triggers/types, or the WTRU may initiate acombined RA procedure for all RA types. The WTRU may be configured orpredefined to prioritize one or several of the triggered RA types. Inone example, the WTRU may prioritize RA procedures for legacy types overRA procedures for small data transfers. The WTRU may prioritize RAprocedures involving connectivity management over RA for small datatransfer, such as RA procedures triggered by mobility, BFR, or systeminformation acquisition. In another example, the WTRU may prioritize anRA triggered by a small data transfer if data from a specific (e.g.configured) LCH or DRB is buffered and can be transmitted over the RAprocedure. In one method, the WTRU may combine triggered RA types into asingle RA procedure. For example, the WTRU may transmit, in the ULdirection, a small data part of an RA initiated by mobility or BFR. TheWTRU may opportunistically include a small data part of such RAprocedure after prioritizing CCCH data and control information (e.g. BFRMAC CE, system info request). In some methods, the WTRU may defer smalldata transmission to a connected mode if another RA procedure istriggered and may result in the WTRU transitioning into connected mode.

Solutions involving segmentation of service data units (SDUs) andtransmitting such segments in subsequent transmissions are describedherein. If a small data packet is too large for a selected (or any)transmission method or methods, or if the amount of buffered small dataapplicable for transmission on a given resource is higher than thesupported/configured transport block size (TBS) of a PUSCH resource, theWTRU may segment an SDU and transmit the segments over multiple smalldata transmission opportunities. For example, an upper later IP packetmay have multiple SDUs, and an earlier SDU may possibly indicate that asubsequent SDU is part of a same IP packet.

In some solutions, a WTRU may indicate to a NodeB (e.g., an eNodeB orgNB) that a small data packet is part of a segmented packet. The WTRUmay also indicate the need for a subsequent grant to transmit small dataor to indicate the amount of remaining small data buffered. possibly viaone or a combination of several methods. In some methods, a WTRU maytransmit, for instance, in MsgA or Msg3, a BSR indicating to the networkthe amount of small data to be transmitted.

In some methods, a WTRU may indicate in a small data transmissionopportunity that a small data packet is part of a segment. The WTRU mayalso indicate how many remaining packets are required to be transmitted.The indication may be carried in part of a MAC CE or in a protocol dataunit (PDU) itself. The WTRU may further transmit a resource requestindication (e.g. a scheduling request (SR) embedded as UCI on a PUSCH oran SR transmitted on a PUCCH) to indicate need for additional UL-SCHresources for one or more logical channels (LCHs). The WTRU may beconfigured with one or more SR configurations to request additionalresources for small data transmission. For example, the WTRU may embedthe SR as UCI on PUSCH on a first TB to request a subsequent resource.

In some methods, a WTRU may indicate to the network that the data packetis segmented, or the WTRU may indicate the need for a subsequent grantto transmit (further) small data, via an RRC message. For example, suchindication(s) may be included in any of a RRC connection resume, a RRCconnection establishment, or a RRC connection re-establishment message.

In some methods, a WTRU may indicate to the network that the data packetis segmented, or the WTRU may indicate the need for a subsequent grantto transmit (further) small data, via transmission in an opportunity ora resource configured or reserved to indicate the need for furtherresources. For example, the WTRU may implicitly provide the indicationfor the need of subsequent resources by transmitting a PDU configured toprovide such indication.

Upon transmission of the indication for subsequent resources for furthersmall data transfer, a WTRU may be configured to monitor one or morePDCCHs on a certain resource (e.g. a CORESET, search space, oraggregation level), possibly for a configured timeframe after providingthe indication, for the reception of a grant and/or PUSCH resourceactivation DCI. In some methods, the WTRU may monitor a PDCCH forsubsequent scheduling during the next ‘on’ duration configured forpaging discontinuous reception (DRX), which may be after a small datatransmission or reception and/or after providing an indication for oneor more subsequent data transmissions. A WTRU may monitor a specificcoreset, search space, or RNTI for the reception of subsequentscheduling. For example, the WTRU may monitor a C-RNTI or I-RNTI forreception of subsequent scheduling. In another method, the WTRU may beconfigured with preamble partitions or groups to indicate the amount ofbuffered small data or the amount of subsequent small data or the amountof buffered small data TBS. For example, the WTRU may select a givenpreamble group if the amount of buffered small data or the amount ofsubsequent small data (data that would not fit in MsgA or Msg3 in theongoing RA procedure) is above a configured threshold or within aconfigured range.

Various embodiments describing WTRU behavior when a small data SDU isbigger than a selected grant size are provided herein. In some cases, aWTRU may perform additional transmissions, e.g. if it has indicated thata small data packet is a segment, or that there are multiple small datapackets to transmit. For example, in some cases, a WTRU may receive aresponse (e.g. in MsgB, Msg2, Msg4) type in a RA procedure, which mayinclude UL grant for transmission of subsequent data (e.g. in INACTIVEstate).

In some cases, a WTRU may change the small data transmission method(e.g. different RA resource, switch between two-step and four-step RACHprocedures, or use a CG). This may depend on the data TBS or whether anodeB response has not been received, possibly due to timer expiry, orit may depend on whether there is subsequent data for transmission. Forexample, the WTRU may send data using a two-step RA procedure and thensend subsequent data using CG. The reverse circumstances may occur aswell. In another example, small data may be sent using MsgA, andsubsequent data may be sent in an UL grant provided by a fallback RAR.

In some cases where a small data SDU is bigger than a selected grantsize, a WTRU may transition to a different state when receiving anindication from the network,

Embodiments directed to transitioning between states or modes aredescribed herein. In some cases, a WTRU may be configured fortransmission or reception of small data in a state other than connectedstate, such as an inactive or idle state. The WTRU may determine toinitiate a procedure for transitioning to a connected state, such aswhen performing RRC connection establishment or RRC connection resumeprocedures based on at least one trigger.

The trigger may be based on at least one of several aspects. Forinstance, the trigger may be based on the resources configured fortransmission or reception of small data, such as configured grants, atwo-step RACH configuration, or SPS configuration. For example, theremay be At least one payload or transport block size for MsgA, and apayload or transport block size may be provided for at least configuredgrant or SPS configurations.

The trigger may be based on a radio bearer and/or LCH configuration.Data for the configuration may be available for transmission, or datamay be received, and the data may include, for example, an RLC mode ofoperation.

The data for the configuration may include at least one parameter forthe LCH configuration such as an LCH priority, a prioritized bit rate, abucket size duration, an allowed serving cell, a subcarrier spacing, amaximum PUSCH duration, and whether the LCH is allowed to be included ina configured grant.

The data for the configuration may be a function of QoS. In some cases,the WTRU may transition to connected mode if it has buffered small datato transmit, but does not have a suitable grant for transmission or doesnot meet the required QoS requirements configured for the associatedbearers. In one example, the WTRU may transition to connected mode if ithas buffered small data for LCHs configured with LCP restrictions notmet by available grants and/or small data transmission methods.

The data for the configuration may include whether logical channel group(LCG) group is configured for the LCH, or the value of the LCG group.The data may also include an SR resource configuration. In anotherexample, downlink data for AM related to the radio bearer or LCHconfiguration may be received.

In some cases, a trigger may be based on at least one property of dataavailable for transmissions over at least one LCH. Such property orproperties may include an amount and/or volume of data or PDU or SDUsizes (e.g. maximum or minimum thereof), a data priority (based, forexample, on the priority of a highest priority LCH), or QoS requirementsassociated with the DRB or DRBs. In some cases, a trigger for initiatingthe transition may be based on an amount of data already transmitted orreceived for at least one LCH; received or determined measurementresults; a received or determined power headroom; or an access classpriority or access identity identified by upper layers (e.g., Layer 2and/or Layer 3). For example, a WTRU may transition into connected mode,or indicate a request to do so (e.g., RRC resume request, RRC connectionestablishment or RRC re-establishment request), upon condition that thesmall data PDU, or SDU, is going to be segmented and/or upon conditionthe amount, or volume, of small data buffered is above a certain orconfigured (e.g., preconfigured) threshold.

In determining to initiate a transition to a connected state, a WTRU mayuse at least one of several triggers (e.g., to transition into connectedmode). For example, one triggering event may occur when data availablefor transmission for a LCH is higher than a configured threshold, orwhen a regular BSR for a LCH would be triggered. Whether this applies toan LCH, and the value of the threshold, may be configured depending on aLCH identity or LCG identity, or a LCH priority. For example, athreshold may be zero (0) for any priority higher than a configuredpriority.

Whether the threshold based trigger applies to an LCH may be configureddepending on whether the LCH is allowed to use a configured grant forsmall data transmission. Whether the trigger applies to an LCH may beconfigured depending on the RLC mode (e.g. AM, TM, UM) for thecorresponding radio bearer. For example, the threshold may be zero (0)if the RLC mode is AM.

Another triggering event may occur when a scheduling request (SR) is orwould be triggered given resources configured for small datatransmission. In some cases, this may only apply for certain SRidentities configured by higher layers, or only if a priority ofcorresponding SR resource is above a priority level.

Another triggering event may occur when transmission of a single MAC SDUwould not be possible using at least one resource configured for smalldata transmission. For example, this may occur in the case a RLC PDUcannot be segmented and is too large to be included in a transportblock, considering the largest available transport block size for MsgAand/or configured grants (such may be dependent on a pathlossmeasurement). In another example, this may occur in the case the LCH isrestricted from using a configured grant for small data transmission.

Another triggering event may occur when a metric for the amount of datatransferred becomes higher than a configured threshold. The metric maycorrespond to a sum of PDU or SDU payloads at PDCP, RLC or MAC sublayersfor a set of logical channels. The set of logical channels may beconfigured. The metric may be reset to zero (0) upon expiry of a timerof a configured duration. The timer may be reset, for example, everytime a MAC, RLC or PDCP PDU is delivered to a lower layer (for uplink)or to a higher layer (for downlink). The metric may be maintainedseparately between downlink and uplink.

Another triggering event may occur upon data reception meeting at leastone of several conditions. One condition may be satisfied when atransport block size is above a configured threshold (e.g. successfulreception for a DL SPS configuration with corresponding transport blocksize above threshold). Another condition may be satisfied upon receptionof a DL SPS assignment corresponding to one of a set of DL SPSconfigurations. Whether the trigger applies to a specific DL SPSconfiguration may be configured. Another condition may be satisfied whendata is received for an LCH, or an amount of data received for at leastone LCH is above a configured threshold. Whether this applies to a LCH,and the value of the threshold, may be configured depending on the LCHidentity or a property or parameter of an associated LCH (i.e. foruplink), such as a paired LCH for RLC AM. The property may be at leastone already described for the triggering based on data available fortransmission.

Another triggering event may occur when one or a combination ofmeasurement events is triggered. For example, such measurement event maybe that a measurement quantity (e.g. RSRP) for a serving cell becomeslower than a configured threshold. Other triggering events may occurwhen a power headroom report is triggered or when a power headroom fallsbelow a configured threshold. Another trigger may be based on an accessclass priority or access identity identified or configured by upperlayers.

In some embodiments, a WTRU may indicate the need or desire totransition to a connected mode (e.g., perform an RRC connection resume,etc.) if any of the above triggers are satisfied.

In some embodiments, a WTRU may compute the amount, or volume, of smalldata which is buffered based on (e.g., as a function of) any of: theDRBs configured for small data transfer, LCHs configured for small datatransfer, and/or a predetermined or configured (e.g., preconfigured)period. For example, a WTRU may compute the amount, or volume, of smalldata which is buffered as the (e.g., total) number of bits stored forany (e.g., all) LCHs and/or DRBs applicable (e.g. configured for) smalldata transmission after constructing the PDU for transmission on anygiven (e.g., each) TTI. The WTRU may include buffered data available fortransmission in any of the RLC layer, the PDCP layer, and/or the RRClayer.

In some embodiments, a WTRU may compute the volume, or amount, afterfilling a grant with data, where the grant may or may not also carry thedata volume/amount report. For example, the data volume or amount can becomputed as an amount (e.g., total) of data available across all logicalchannels configured for small data, and may also include data not yetassociated with a logical channel, after any (e.g., all) MAC PDUs forthe TTI and/or grant have been built. For example, a WTRU may beconfigured (e.g., preconfigured) with a data volume threshold totransition into connected mode, or request to transition into connectedmode, upon condition that an amount or volume of buffered small data isabove the threshold. A WTRU may compute the amount of buffered smalldata before constructing a small data PDU on a given resource, such as aPUSCH resource (e.g., PUSCH resource on which the indication totransition to connected mode and/or subsequent data is multiplexed). TheWTRU may then include the indication to transition to connected modeand/or subsequent data such as upon condition the amount and/or volumeof small data is above the threshold (e.g., prior to running the LCPprocedure).

In another example, a WTRU may compute the amount of buffered small dataafter constructing a small data PDU on a given resource, such as a PUSCHresource (e.g., PUSCH resource on which the indication to transition toconnected mode and/or subsequent data is multiplexed). The WTRU may theninclude the indication to transition to connected mode and/or subsequentdata such as upon condition the amount and/or volume of small data isabove the threshold (e.g., prior to running the LCP procedure).

In some embodiments, a WTRU may include (e.g., only include) data thathas arrived at least a certain predetermined or configured (e.g.,preconfigured) period prior to computing the volume or amount ofbuffered small data or prior to the small data transmission start. Forexample, a WTRU may include (e.g., only include) data that has beenbuffered (e.g., is in the buffer) for at least a certain predeterminedor configured period (e.g., for the data volume computation). In anotherexample, the UE may compute the volume or amount of small data as adifferential data volume as the data volume difference as compared to apreviously reported (e.g., last reported) value.

In some embodiments, a WTRU may include a data volume report, such asalong with the indication to transition to connected mode (or requestthereof) and/or the indication for a subsequent small data transfer. Thedata volume report can be included as any of a MAC CE (or part thereof),indicated in a MAC subheader, and/or indicated as part of an RRCmessage. The data volume report may also be included as part of a BSRMAC CE or constructed as a separate MAC CE. It should be understood thatthe data volume may be computed per any of the foregoing examples orusing any combination thereof.

Embodiments directed to load control, contention resolution, and backoffmay be described herein. A WTRU may be in various contention scenariosduring small data transmission. The collision scenarios described belowmay be possible alone or in combination.

In some scenarios, a WTRU supporting small data transmission andtransmitting small data part of a RA procedure may cause a collisionwith another WTRU supporting small data, for instance, by selecting thesame resources configured for uplink small data transmission.

In one case, there may be a collision between PRACH and PUSCH resources.The colliding WTRU may be transmitting small data on the same PRACHresource. The PRACH resource may be a two-step or a four-step RAresource.

In another case, a PRACH-only collision may occur. A colliding WTRU maynot be transmitting small data on the PRACH resource (e.g. the WTRU maybe performing a legacy RA procedure on the same PRACH resource). ThePRACH resource may be a two-step or a four-step RA resource. Thecolliding WTRU may be transmitting small data and have selected adifferent PUSCH resource mapped to the same RO.

In another case, a PUSCH-only collision may occur: The colliding WTRUmay be transmitting small data on the same PUSCH payload resource oftwo-step RA resources. In one example, the PUSCH resource may becontention-based while the PRACH resource may be contention free; insuch case, WTRUs may collide on the PUSCH payload resources but not thePRACH resource. In another example, the PRACH resource may be associatedwith one or multiple PUSCH resources, were both PRACH and PUSCHresources are contention-based.

In some scenarios, a WTRU supporting small data transmission andtransmitting data on a two-step RA resource may collide with a legacyWTRU not supporting small data transmission. In one case, the collidinglegacy WTRU may be performing a legacy four-step RA procedure on thesame PRACH resource, given that in NR Release 16, RACH occasions may beshared between two-step and four-step RA procedures. In another case,the colliding legacy WTRU may be performing a legacy two-step RAprocedure on the same PRACH and/or associated PUSCH resource.

In some scenarios, a WTRU supporting small data transmission andtransmitting data on a four-step RA resource may collide with a legacyWTRU not supporting small data transmission. The colliding legacy WTRUmay be performing a legacy four-step RA procedure on the same PRACHresource, given that in NR Release 16 RACH occasions may be sharedbetween two-step and four-step RA procedures.

Embodiments directed to collision determination and avoidance andcontention resolution are described herein. In some solutions, aftertransmission of the Msg1 or MsgA parts of a RA procedure with or forsmall data transmissions, the WTRU may monitor for MsgB or Msg2transmissions on a certain configured CORESET, search space, or PDCCHresources, or the WTRU may monitor for an RNTI unique to the WTRU (e.g.I-RNTI or C-RNTI), and/or a separate/small data-RA-RNTI. Suchconfiguration may be delivered to the WTRU by RRC or broadcastsignalling.

The WTRU may start the RAR or MsgB monitoring window after thetransmission of Msg1 or MsgA, during which the WTRU may monitor thePDCCH for reception of Msg2 or MsgB. An enhanced Msg2 or MsgB mayprovide at least one indicator upon reception of which the WTRU maydetermine that a collision has occurred. Such indicator or indicatorsmay be a RAR, possibly containing an uplink grant to retransmit a MsgApayload (e.g. a fallback RAR) or to (re)-transmit small data (e.g. witha different RV); a backoff indication; or a contention resolution ID. Acontention resolution ID may indicate to differentiate or identify oneor more of the colliding WTRUs or the WTRU type. This may be indicatedby a certain RNTI associated with the WTRU (e.g. I-RNTI or C-RNTI), orthe PRACH resource may be used to schedule the RAR (e.g. the RAPID,RA-RNTI or msgB-RNTI). For example, the WTRU may determine that aT-CRNTI is applicable if it receives an indication in an enhanced RARformat.

The indicator or indicators introduced above may also be an RA-typeidentification (e.g. RA by a small data WTRU vs. RA by legacy WTRU). AWTRU may determine that the such indication is for itself if an explicitbit in the MAC RAR payload is flagged (e.g. to differentiate from WTRUsperforming legacy two-step RA procedures), if a certain RNTI associatedwith the WTRU or the PRACH resource is used to schedule the RAR, if anexplicit indication is signalled by DCI, or if an implicit indication isconveyed from the used PDCCH resource (e.g. CORESET or search space).The indicator introduced above may also be a timing advance command.

In some solutions, a WTRU may also determine that a Msg1/MsgBtransmission was unsuccessful (e.g. a collision occurred) if it does notreceive a RAR or MsgB by the expiry of the RAR/msgB window, or if itdoes not receive an indication that matches the WTRU's identity, theidentity of the selected PRACH resource, and/or the RA type that wasinitiated. The WTRU may monitor for both MsgB and RAR during the RARmonitoring window, e.g. when the RACH occasion (RO) is shared betweentwo-step and four-step RACH procedures. When the RO is shared betweentwo-step and four-step RA procedures, the WTRU may determine that a MsgAtransmission was unsuccessful—including the transmission of the smalldata payload—if the RAR monitoring window has expired and the WTRU hasnot received a success RAR in MsgB addressed to the WTRU identity, theWTRU's PRACH resource, and/or the WTRU RA type. The WTRU may receive aMsgB with a success RAR—or a number of RARs indicating success that aremultiplexed—which does not contain the WTRU identity. In some cases, ifthe RACH resource is shared between WTRU supporting small data andlegacy WTRUs, the WTRU may consider the RAR reception successful if theRA type identification was signalled or indicated part of the RARpayload or the PDCCH that scheduled the RAR.

After a WTRU determines that a collision has occurred, that the datapayload was not received successfully, or when the WTRU has not receiveda RAR or msgB, and/or counted a number of failed data transmissionattempts, the WTRU may perform one or more procedures. In some cases,the WTRU may retransmit MsgA—after backoff, if indicated—if itdetermines that a collision has occurred, no RAR was received (e.g.success RAR or fallback RAR) by the expiry of the msgB window, and/orthe UL grant—if provided in MsgB—is not for the WTRU. The WTRU maydetermine whether the grant is for itself per the aforementionedidentification conditions.

In some cases, the WTRU may transmit Msg3 (i.e. fallback to a four-stepRA procedure), which may include the MsgA payload, if for example agrant was included and a WTRU identification matching the WTRU ID, WTRUtype, and/or PRACH resource was included or indicated in the RAR.

In some cases, a WTRU may retransmit Msg1 (preamble only)—after backoffif indicated—after falling back to a four-step RA indication, after notreceiving a RAR or contention resolution in a four-step RA procedure,and/or after a number of unsuccessful attempts for transmitting datapayload part of two-step RA procedure.

In some cases, a WTRU may retransmit the PUSCH payload without thepreamble. For example, the WTRU may receive an indication in RAR/MsgBindicating that the payload was not successfully decoded/received (e.g.NACK). The WTRU may alternatively make this determination by receiving aRAR that does not match the WTRU's identity, though it may match theidentity of the PRACH resources used (e.g. an RA/MsgB-RNTI). The RAR orMsgB may be addressed to the WTRU identity or an identity associatedwith the selected PRACH resource. Upon reception of indication with theWTRU identity, the WTRU may retransmit the payload on the PUSCH resourceassociated with the previously selected PRACH (without preambleretransmission), retransmit the payload on a different PUSCH associatedwith the same PRACH resource, or retransmit the payload on an uplinkgrant provided in RAR or MsgB, if provided.

In some cases, a WTRU may retransmit the small data or the MsgA payloadusing a different small data transmission method (e.g. using a four-stepRA procedure—or a two-step procedure if four-step was used— or using aconfigured grant). The WTRU may further perform this, for example, afterN unsuccessful attempts or after a certain timer has elapsed. The WTRUmay further perform this after receiving an indication to do so (e.g.,an indication to fallback to a four-step RA procedure, fallback totransmission on CG, or fallback to transmission on a different two-stepRA resource) in part of the msgB transmission. The WTRU may stop theongoing RA procedure after switching to a different small datatransmission method (e.g. two/four-step RA, on a CG, etc). In somecases, a WTRU may report a link failure to upper layers.

Embodiments directed to load control and backoff are described herein. AWTRU may receive an enhanced backoff indication part of Msg2 or MsgBthat includes one or more information. Such information may include, forexample, an applicability indication to one or more WTRUs (a group orsubset of WTRUs). For instance, a small data bit may be included part ofa backoff sub-PDU to indicate that backoff is only applicable to legacyWTRUs or visa-versa (e.g., that backoff is only applicable to small dataWTRUs). In another example, the applicability indication may be a uniqueID that indicates a subset of WTRUs (e.g. a small data RNTI, an RNTIthat corresponds to the identity of single WTRU C-RNTI or I-RNTI). Theindication may be conveyed implicitly from the PDCCH resource (e.g. aCORESET or search space) used to schedule the backoff sub-PDU. Forexample, the WTRU may monitor two search spaces (one for a fallback RARand another for a RAR indicating success); the WTRU may determine thatbackoff is applicable if the BI was received on one of the search spaces(e.g. the search space associated with two-step RA), and may not applythe backoff if it was received on the other search space.

The information may include, for example, an indication bit to signal tothe WTRU to switch to the different small data transmission method (i.e.different RA resource, switch between two-step or four-step RAprocedures, or use a CG) after backoff.

The information may include, for example, an applicability indication toa subset of RA types (e.g. only for four-step RA, only for two-step RAprocedures, RA by a small data WTRU vs. RA by legacy WTRU, RA for BFR,RA for mobility, etc.). The WTRU may determine that such indication isfor its RA type if an explicit bit in the MAC RAR payload is flagged(e.g. to differentiate from legacy two-step RA WTRUs), if, for example,a certain RNTI associated with the WTRU or the PRACH resource is used toschedule the RAR, if an explicit indication is signalled by DCI, or ifan implicit indication is conveyed from the used PDCCH resource (e.g.CORESET or search space). In some cases, the WTRU may determine thatsuch indication is for its RA type implicitly according to the RA typeit has used. For example, a predefined rule may be used to signal RAtypes with reduced backoff or no backoff.

The information may include, for example, an indication to switch to adifferent RACH resource, a different PUSCH payload resource associatedwith the selected PRACH resource, a switch between two-step andfour-step RA, or a different small data transmission method (e.g. usinga CG).

A WTRU may able to determine that a backoff indication is intended onlyfor legacy WTRUs, such as when the WTRU receives a RAR indicatingsuccess that is addressed to a small data-RNTI (e.g. not supported bylegacy WTRUs) or its I/C-RNTI, in addition to the backoff indication.The WTRU may able to determine that the backoff indication is intendedonly for legacy WTRUs, such as when the WTRU receives a RAR indicatingsuccess on a separately configured CORESET or search space that legacyWTRUs do not monitor. The WTRU may thus apply the indicated backoffconditionally on not receiving a success RAR by the expiry of theMsgB/RAR window.

A WTRU may fallback to a legacy RA procedure, retransmit the small datausing a different method (two-step RA, four-step RA, on a CG), abort theongoing small data transmission procedure, start a new random accessprocedure, and/or transition into connected mode after N unsuccessfulattempts of small data transmission, after a certain timer has elapsed,or after reception of an indication to do so in the backoff MAC sub-PDUpayload.

The WTRU may attempt to select a different preamble group or PRACHresource, possibly for a different small data payload size, after anumber of failed transmission attempts or timer expiry. For example, theWTRU may have selected a PRACH resource or preamble group x over whichto transmit a payload of size y and failed to successfully transmit thepayload N times (N may be configured, for instance, by RRC signaling).After N failed attempts, the WTRU may select a different preamble groupfor a smaller payload size less than y. The WTRU may construct a new TBto match the TB size of the selected preamble group and may flush theMsg3 or MsgA payload buffer for the associated HARQ process.

Embodiments directed to RA prioritization and/or differentiation aredescribed herein. In some solutions, a WTRU may apply prioritized,scaled, or different backoff or power ramping if small data wastransmitted (e.g. previously included in a MsgA/Msg3 payload) or datafrom certain LCHs was included in the MsgA or Msg3 payload (e.g. LCHsconfigured as applicable for small data transmission). In othersolutions, a WTRU may apply non-prioritized/non-scaled backoff or powerramping if small data was transmitted (e.g. previously included inMsgA/Msg3 payload), data from certain LCH(s) was included in the MsgA orMsg3 payload (e.g. LCHs configured as applicable for small datatransmission).

In other solutions the WTRU may apply power ramping only to the PUSCHpayload part or to both preamble and payload parts. For example, if anindication was received in MsgB or Msg2 indicating a payloadretransmission (e.g. NACK) or a fallback RAR was received addressed toRA/MsgB-RNTI, the WTRU may determine that only the payload transmissionfailed, and thus, the WTRU may power ramp only the payload transmission.

Various embodiments for performing low-latency transmissions of smalldata are described herein. In some embodiments, a WTRU may be configuredwith conditional or contention free RA or CG resources, such asfour-step, two-step CFRA, and/or other CG resources. possibly with alist of applicable logical channels, DRBs, and/or SRBs. The WTRU may beconfigured with a one-to-one or a one-to-many mapping between a CFRApreamble and a PUSCH resource. The WTRU may persist in using or havingdedicated CFRA configurations upon transitioning into inactive state.The WTRU may determine the UL grant and the associated HARQ informationfor the MsgA according to the selected PUSCH resource and an associatedRRC configuration.

In some embodiments, a WTRU may select conditional/contention-freeresources if the highest priority data or LCH with buffered data forsmall data transmission is above a threshold, and/or if CCCH or SRB datais buffered for transmission. The WTRU may selectconditional/contention-free resources if at least one LCH with buffereddata for small data transmission is configured to be applicable for aconditional/contention-free small data resource. The WTRU may selectconditional/contention-free resources if at least one LCH with buffereddata for small data transmission is configured as applicable for smalldata, i.e. per LCH/DRB/LCG/QoS flow configuration small dataapplicability by RRC configuration. In some methods, the WTRU may selecta conditional/contention-free resource based on a latency requirement(e.g. traffic periodicity, survival time, and/or HOL delay) of anassociated LCH with buffered small data. For example, the WTRU mayselect such resource if the traffic periodicity, survival time, and/orHOL delay of the associated LCH with buffered small data is less than athreshold or can be maintained using the selected resource. A WTRU mayprioritize the selection of a two-step RA or CG without preamble smalldata transmission methods over four-step RA methods, if the requiredlatency cannot be met with small data transmission over four-step RA

In some embodiments, a WTRU may select a conditional/contention-freeresources if a measured channel condition is above a configuredthreshold. For example, the WTRU may select a certain conditionalresource if RSRP is above a threshold. The WTRU may selectconditional/contention-free resources if the uplink timing ismaintained, e.g. if an uplink timing synchronization timer is running,if the estimated propagation delay is less than a configured threshold,and/or if the WTRU receives or maintains a certain UL timing advancecommand.

In some embodiments, the WTRU may select conditional/contention-freeresources if it receives a PDCCH paging with a specific RNTI (e.g.,I-RNTI or P-RNTI), if it receives an indication on PDCCH on apreconfigured coreset or search space, if it receives associateddownlink control information or data, and/or if it receives downlinksmall data. For example, a WTRU may receive (e.g., dynamic) signallingto suspend and/or resume the usage of a small data resource. A WTRU mayreceive an indication by DCI and/or receive an indication in a MAC CEthat indicates the suspension or resumption of small data transfer forany of one, a subset, or all small data transmission resource. The WTRUmay receive such indication in any of a PDSCH msgB, msg2, and/or msg4),in a DL TB and/or as part of a Li or L2 payload. The WTRU may alsoreceive such indication on another resource, such as PDCCH (e.g., viaDCI). Upon reception of a suspension indication. the WTRU may stop usingthe associated small data resource for a period (e.g, until receiving aresumption indication and/or upon expiry of a backoff timer). The WTRUmay start a backoff timer upon reception of a suspension indication.Upon expiry of the backoff timer, may then resume using the resource forsmall data transfer.

In some embodiments, the WTRU may fall back to small data transmissionon contention-based resources, e.g. if the small data transmission doesnot succeed on the conditional/contention-free resources. The WTRU maystart a timer after transmission of uplink data on aconditional/contention-free resource. The WTRU may stop the timer uponsucceeding in transmitting small data on the conditional/contention freeresource. Upon expiry of the timer, the WTRU may attempt to retransmitsmall data on contention-based resources. In one method, the WTRU maystart with attempting to transmit small data on a contention basedresource (e.g. RA or CG based) then switch to transmit or retransmitsmall data on conditional/contention-free resources after receiving anindication from the nodeB (e.g., gNB). The WTRU may transmit onconditional/contention-free resource after receiving an indication fromthe nodeB, whereby the indication can be signalled to the WTRU in PDCCHsignalling, indicated part of Msg2 or MsgB, or indicated using a MAC CEor part of the MAC CE.

In some embodiments, such as in legacy systems, a WTRU may select atwo-step RA resource only if RSRP is above a configured threshold.Further, the WTRU can select CFRA resources if a RSPR is above athreshold. the WTRU may be configured with both two-step and four-stepresources in the same BWP.

In one method, the WTRU may select CFRA and/or two-step RA resourceseven if RSRP is lower than threshold for selecting two-step RAresources. For example, the WTRU may select two-step CFRA if timingalignment timer is running and/or if small data is buffered for a LCHconfigured for low latency traffic for transmission on the CFRAresource. For example, the WTRU may select two-step CFRA if uplinktiming is maintained by the WTRU, if propagation delay is compensatedfor, and/or if the WTRU has not moved since transitioning to IDLE orINACTIVE state. The WTRU may ignore the RSRP threshold for selectingcontention-free and/or two-step RA resources, if a two-step CFRAresource is available and can be selected (e.g. if RSRP is above theconfigured threshold applicable for selecting the CFRA resource). TheWTRU may monitor a PDCCH transmission addressed to I-RNTI and MsgB-RNTIfor reception of MsgB or a fallback RAR, possibly if it selected atwo-step CFRA resource though the RSRP is less than the thresholdconfigured for two-step RA resource selection. To enable fallback toCBRA, the WTRU may limit transmitting small data on CFRA resources onlyif the active BWP contains CBRA resources. To enable fallback tofour-step RA procedure, the WTRU may limit transmitting small data onCFRA resources only if the active BWP contains four-step RA resources.The WTRU may fall back to CBRA resources and/or four-step RA resourcesto retransmit the small data after a number of configured attempts onCFRA resources. The WTRU may fall back to CBRA resources and/orfour-step RA resources to retransmit the small data after expiry of atimer. The WTRU may start a timer at the first attempt to transmit smalldata on contention-free and/or two-step RA resources, possibly only ifthe RSRP is less than the threshold required for selectingcontention-free and/or two-step RA resources.

Various embodiments relating to HARQ feedback and retransmission aredescribed herein. In a RA based procedure, a WTRU may send a limitedamount of data in a Msg3 or MsgA transmission on a PUSCH. In four-stepRACH procedure, the WTRU may determine PUSCH time and/or frequencyresources with an UL grant in a Msg2 transmission. In two-step RAprocedure, the PUSCH time/frequency resources may be determined by anassociation with a preamble index (RAPID). The WTRU may determine itsdata transmission is successful when it detects a Msg4 transmissionaddressed to its RNTI or when it detects a MsgB transmission with a RARindicating success. A WTRU may acknowledge successful reception of aMsg4 or MsgB by sending an acknowledgement (ACK) over a PUCCH. However,a WTRU may send data larger than supported by one Msg3/MsgA procedure. AnodeB may include a subsequent UL grant in Msg4 or MsgB, but a WTRU maybe unable to determine if its subsequent UL transmissions in grants aresuccessful. In the following, solutions may be described for the WTRU toverify the subsequent data transmitted on the subsequent grant.Solutions may also be described for sending multiple retransmissionswithout waiting for HARQ feedback.

In some solutions, a WTRU may perform HARQ procedures for one or moreburst transmissions following a Msg3 or MsgA transmission. In one suchsolution, a WTRU may use an implicit ACK notification based on aconfigured timer. For example, a WTRU may send its subsequent data burstand may start a timer at the start or end of the burst. The WTRU may beconfigured to monitor for an ACK which may be transmitted in a Msg4 orMsgB transmission. A WTRU may determine to perform retransmission of theburst if no ACK is received within the timer's validity period.

In some solutions, a WTRU may determine that additional bursttransmissions failed if a WTRU detects a retransmission request. Forexample, a Msg4 or MsgB transmission may carry an UL grant for the WTRUto transmit additional data bursts. A WTRU may transmit the additionalbursts and the retransmission request may be determined as the WTRUmonitors for an explicit RAR, such as a retransmissionRAR, indicatingretransmission resources. A NodeB may monitor for the additional databursts on the resources indicated by the UL grant. A WTRU may determinethat a retransmissionRAR MAC PDU indicates that the subsequenttransmission failed and need to be retransmitted. The retransmissionRARmay be carried in a Msg4/MsgB addressed with a Msg4-RNTI or MsgB-RNTI. AWTRU may be configured with a timer window and a WTRU may keepmonitoring for a retransmissionRAR within the timers validity period. Ifa WTRU does not receive a retransmissionRAR, the WTRU may determine thatits transmission burst has been successfully received. In anothermethod, if a WTRU does not receive a retransmissionRAR by the expiry ofthe timers validity period, the WTRU may determine that its transmissionburst is unsuccessful, the WTRU may retransmit the small data payload onthe next applicable PUSCH and/or PRACH resource.

In some solutions, a WTRU may receive an ACK/NACK based on a paging. AWTRU may receive an indication in MsgB with an RNTI for a pagingchannel. A WTRU may monitor for a paging channel with the specific RNTIand/or a specific time window. The paging channel may contain a messageindicating an ACK or NACK and the time/frequency resources for aretransmission if needed. In some methods, the WTRU may monitor PDCCHfor HARQ feedback the next ‘On’ duration configured for paging DRX,after small data transmission or reception and/or subsequent small datatransfer. The WTRU may monitor a specific coreset, search space, or RNTIfor the reception of HARQ feedback or retransmissions. The WTRU mayfurther provide HARQ feedback for received DL small data during the next‘On’ duration configured for paging.

Solutions relating to HARQ feedback-less transmissions and TBrepetitions are described herein. To reduce latency and increasereliability, a WTRU may determine to send multiple repetitions of a TBbefore receiving a HARQ response from the nodeB. The WTRU may stoptransmitting the repetitions upon determining an ACK or counting acertain number of repetitions. The WTRU may determine the resourceconfiguration to be used for the repetitions in the one or a combinationof ways. For example, a WTRU may determine to reuse the same resourcesfor the retransmission as the original transmission with a timing offsetfor each repetition, or a WTRU may be configured with retransmissionparameters as a function of the retransmission index.

In some cases, a WTRU may determine the location of the time and/orfrequency resources based on a preamble. The preamble may bepreconfigured with a link to multiple sets of resources in time orfrequency. The WTRU may initiate a transmission using a RACH procedureby sending a preamble and transmitting the TB repetitions over themultiple linked resources. The nodeB may detect the preamble anddetermine on which resources the repetitions are sent by the WTRU. Themultiple resources may be linked across the same RACH occasion in thesame time instant and different frequency instants, or across differenttime instants.

In some cases, a WTRU may determine the parameters of the TB repetitionsbased on the preamble. For example, a preamble may be linked to multipleredundancy versions (RVs) configured in a sequence and the WTRU maydetermine to use a sequence of RVs based on the sequence of TBrepetitions.

In some cases, a WTRU may determine the timing of the TB repetitionsbased on the preamble. For example, the preamble may be linked to one ora plurality of timing values where the WTRU may determine the timing ofthe TB repetition to send. The WTRU may use multiple explicit timingvalues as offsets relative to the preamble transmission to determine thetime location of each TB repetition.

In some cases, a preamble may be linked to one offset from which theWTRU may determine the repetitions to be sent; the repetitions may thenbe sent as a function of the offset. The WTRU may be preconfigured withan offset or it may receive the timing offset dynamically as T_offset.For example, the WTRU may determine the time location of repetition 1 asT_1=i1*T_offset, and the time location of another repetition asT_2=i2*T_offset, where i1 and i2 may be, for example, the repetitionnumber.

A WTRU may receive, in MsgB, a RAR that may contain an indication oftime/frequency resources over which the WTRU may send its subsequentdata transmissions. The time/frequency resources for retransmissions maybe linked to different RACH occasions in the subsequent timinginstances. MsgB may contain an index of the RACH occasions from which aWTRU may determine the available PUSCH resources for its subsequenttransmission bursts.

In some embodiments, a WTRU may perform a hybrid RA procedure and use aconfigured grant to transmit an additional payload. For example, theWTRU may initiate a RA procedure and then may use a configured grant tosend a payload that may be larger than supported in the RA procedure bythe payload resources (e.g., Msg3 or MsgA). The RA procedure may be usedto determine or trigger the configured grant resources to use. Forexample, a WTRU may indicate a subsequent transmission part of the RAprocedure, and may then receive the configuration for the configuredgrant (e.g., in a MsgB or Msg4).

The hybrid solution may be supported in one or more ways. For instance,a WTRU may send a preamble and/or a PRACH resource, and the preamble maybe linked to a configured grant resource index. The preambles and/or ROsmay be partitioned according to the random access preamble ID (RAPID)into regions where the nodeB may implicitly determine which configuredgrant is used by the WTRU. For example, preambles 1:N1 may be linked toconfigured grant (CG) resource 1 and/or TBS 1, and preambles N1+1:N2 maybe linked to CG resource 2 and/or TBS 2. A WTRU may determine which CGresource to use based on payload size and/or latency. For example,reception of a predetermined or configured message (e.g., a MsgB orMsg4) may implicitly activate the CG resource associated with the RAresource, or may provide a (e.g., explicit) configuration of the CGresource.

In some solutions, the WTRU may determine a configured grant resourceindex and may include one or more indices in a Msg3 or MsgA payload. TheNodeB may determine that the payload contains a configured grant indexbased on the RAPID or based on the location of the payload resources.For example, one preamble may link to a subset of PUSCH resources whichmay be reserved for requests for a configured grant. The nodeB maydecode the preamble and may expect to receive the index of theconfigured grant in the corresponding payload.

In some solutions a WTRU may indicate a priority level in Msg3 or MsgAand may use a configured grant resource that may be associated to thepriority level. For example, some resources may be reserved for URLLCtraffic. In other solutions, the WTRU may scramble its MsgA payload witha special RNTI (e.g. smallData-RNTI) to implicitly indicate to the nodeBthe index of the used type 1 configured grant. The smallData-RNTI valuemay be partitioned such that the WTRU may choose values within a rangeto implicitly indicate the configured grant resources to be used. Forexample, the MsgA PUSCH scrambling may be initialized with a seeddepending on the configured grant index.

In some solutions, a WTRU may send a preamble to trigger the activationof a type 2 configured grant resource. For example, a WTRU may transmita preamble that may be configured to trigger the nodeB to send a PDCCHaddressed to a CS-RNTI, C-RNTI, or I-RNTI upon detection of thepreamble. The WTRU may monitor one or more PDCCHs for the activation ofthe applicable configured grant after transmitting the indication onMsg1 or MsgA (e.g., as an indication for a subsequent datatransmission). The WTRU may monitor one or more PDCCHs for CGactivation, or deactivation, after small data transmission (e.g., onMsgA, Msg3 and/or CG), after successful completion of a RACHtransmission, and/or after providing a subsequent data transmission.

In some solutions, a WTRU may include an indication in a MsgA payloadthat the WTRU requests for a configured grant (e.g. BSR). For example,such an indication may be an indication for subsequent data transmission(e.g., a flag bit), a BSR MAC CE, a data volume MAC CE, and/or a smalldata BSR MAC CE.

In some solutions, a WTRU may trigger a type 2 configured grant based onthe scrambling used for msg3/msgA payload. For example, a WTRU may usean RNTI to scramble its data payload and the RNTI may be partitionedaccording to payload ranges required by the WTRU. The nodeB may decodethe RNTI and it may have an indication of the payload required by theWTRU. The gNB may trigger a type2 configured grant with a resourceconfiguration satisfying the WTRU's request.

In some embodiments, a WTRU may receive a dedicated grant (e.g. aconfigured grant), the UE may prioritize the selection of such grant forthe transmission of small data over other available RACH resources,possibly conditioned on: not changing serving cells, not changing thecell group, not changing RNAs, and/or having the UE context known at thereceiving gNB. In one method, the UE may deem a CG resource usable in acell in INACTIVE/IDLE state if a successful RACH procedure was performedin that serving cell—or cell group-prior to using the CG.

Upon reception and/or activation of a CG (e.g., an INACTIVE/IDLE CG), aWTRU may use a CG for small data transfer for a configured period oftime, after the expiry of such period the UE may fallback to usingRACH-based small data transfer. Such period can be determined by the TAtimer or a separate new TA timer associated with the CG.

Embodiments directed to HARQ process ID provisioning in idle/inactivemodes are described herein. In legacy RA, the WTRU may use HARQ processID ‘0’ for storing and transmitting the PDU associated with msg3 orMsgA. The WTRU may need to transmit multiple small data TBs withoutgoing into connected mode.

The WTRU may be configured or predefined with a subset of HARQ processesapplicable for small data transmission, e.g. in INACTIVE or IDLE modes.The WTRU may be configured by semi-static or broadcast signalling withthis subset of HARQ process IDs. The WTRU may be indicated the HARQprocess ID applicable for small data transmission in Msg2 or part ofPDCCH signalling.

In some methods, the WTRU may select the HARQ process ID associated withdata transmission, e.g. from a pool of configured HARQ process IDs. TheWTRU may indicate the selected HARQ process ID associated with smalldata transmission part of the PUSCH transmission (e.g. UCI on PUSCH,part of MsgA or a CG transmission without preamble), part of the MAC CE,an indicated part of MsgA payload, or part of the small data payload.

For two-step RA, the WTRU may be configured or predefined with a mappingbetween a subset of PRACH and/or PUSCH resources associated with MsgAand one or more HARQ process IDs, where the resource can be specified bythe time, frequency, and/or preamble domain. For example, the WTRU canbe configured with a mapping between PUSCH resource(s) x and HARQprocess ID y, PRACH resource(s) x and HARQ process ID y, and/or a groupof preambles and a HARQ Process ID.

In some methods, the WTRU may determine the HARQ process ID from thetime and/or frequency used to transmit the preamble/MsgA, from theRA-RNTI, and/or from MsgB-RNTI. The WTRU may be predefined with aformula to determine the HARQ PID to use for a small data UL TB. TheWTRU may determine the PID from the PRACH and/or PUSCH occasion used totransmit the small data. The WTRU may be configured with a pattern suchthat a subset of PRACH and/or PUSCH occasions share the same HARQprocess ID periodically. For example, the WTRU may cycle consecutivelythrough the configured number of HARQ-Processes applicable for smalldata transmission, whereby the WTRU may increase the HARQ PID once perconfigured incremental period. For example, a sample formula can be:

Process ID=[floor(CURRENT_slot/periodicity/scale)] modulonrofHARQ-Processes

where “current slot” may be the slot used to transmit PRACH or PUSCHassociated with the small data. The WTRU may only count—or increment thecount-slots applicable for RACH and/or PUSCH applicable for datatransmission. This can be alternatively replaced with a currentlysymbol. In another example, the current slot can be computed as “currentslot number modulo pattern,” where “pattern” may be the number of slotsused for the same HARQ PID. “Periodicity” may be the periodicity of thePRACH or PUSCH resource applicable for small data transmission. The WTRUmay consider the periodicity as the period between PRACH and/or PUSCHresources that do not share the same HARQ Process ID, or the periodbetween PRACH and/or PUSCH resource that are configured to have the sameprocess ID. “Scale” may be 1 by default or a different value that can beused by the NW to scale the increase. “nrofHARQ-Processes” may be thenumber of HARQ process applicable for small data transmission; suchvalue may be configured by RRC configuration.

In some methods, the WTRU may start a parallel RA procedure for eachsmall data transmission associated with a different HARQ process ID. TheWTRU may maintain separate preamble and power ramping counters per RAprocedure. For small data transmitted without preamble, the WTRU maymaintain a CG timer per HARQ process applicable for small datatransmission.

In some embodiments, the WTRU may toggle NDI and/or flush the buffer(s)for HARQ process ID(s) associated with small data transmission in IDLEor INACTIVE on one or more of several conditions. For example, the WTRUmay toggle NDI and flush the buffer(s) for HARQ process ID(s) associatedwith small data transmission in IDLE or INACTIVE after succeeding asmall data transfer procedure, upon successful reception of MsgB (e.g.success RAR), upon providing HARQ-ACK==ACK for MsgB, upon successfulreception of Msg4, upon succeeding the associated RA procedure, and/orupon receiving a HARQ-ACK value for the small data TB transmitted,and/or upon expiry.

As described herein, in some embodiments, a WTRU may be able to transmitsmall data in inactive or idle modes using a configured grant PUSCHresource, without an associated preamble transmission. Such transmissioncan be viable when uplink timing advance is not necessary, already knownor maintained, or does not change drastically. In some cases, the WTRUmay receive a configuration (e.g. by broadcast or RRC signaling) whethersmall data transmission is applicable on the cell for one or moreconfigured grants in idle and/or inactive modes. Such configuration canbe either dedicated (per Cell ID, and in HO command) or provided bybroadcast system information signalling.

In some solutions, the configuration could indicate whether or not theWTRU may use small data transfers (i.e., without transitioning to aconnected mode) and if so, whether or not it should use PRACH and/ortransmit an accompanying preamble. In some methods, the WTRU may beconfigured with criteria for using an accompanying PRACH, such as arange of channel conditions, TA, S-measure, a CRE region, or L3 channelmeasurements. In some cases, the WTRU may be further configured (e.g. bybroadcast or RRC signalling) with associated transmit power parameters.A nominal target power, Po, may be broadcasted, possibly also per rangebased on factors such as an S-measure.

Embodiments directed to resource selection for HARQ processes aredescribed herein. In some solutions, configured grants may be sharedwith other WTRUs, thus creating a possibility of contention andcollision. A WTRU may repeat a TB transmission in the time and/orfrequency domain for example, using frequency hopping, TTI bundling withRV sequencing, or one or a combination of other methods. Collisionsbetween WTRUs may occur due to more than one WTRU selecting the sametime/frequency resource for small data transmission, or due to uplinktiming misalignment in inactive or idle modes. The CG resource used forsmall data transmission in inactive or idle mode may be shared withother WTRUs in connected mode, or the CG resource may be shared withWTRUs using the same resource for transmission of the MsgA PUSCHpayload.

In some solutions, in connected mode, if a collision on CG happens andthe network cannot decode a conflicting transmission, a network (NW) mayissue a dynamic grant to a WTRU to separate the collisions. Given theWTRU may not monitor C-RNTI in inactive mode, the WTRU may monitor oneor more PDCCHs scrambled by I-RNTI, C-RNTI, CS-RNTI and/or another smalldata RNTI during a monitoring window after the UL transmission. The WTRUmay start a PDCCH monitoring window, such as a CG response window,during which the WTRU may monitor the PDCCH, possibly on certainconfigured CORESETS, search spaces, and/or RNTIs (e.g. I-RNTI, C-RNTI,CS-RNTI an/or a small data CG-RNTI). The window and related parametersmay be configured by broadcast or RRC signaling for example, per cell orper CG resource. For example, upon expiry of the CG response window, theWTRU may determine the small data transmission to have failed, mayinitiate a small data retransmission on a PRACH resource, and/or mayswitch to a different BWP or serving cell to perform a retransmission.The UE may start, or restart, the CG response window after any ofperforming a new small data transmission, receiving a TA value,receiving a TA command (e.g., via MAC CE), receiving an indication for aretransmission grant (e.g., via DCIO, and/or receiving any of a Msg2,Msg4 or MsgB.

In some solutions, a WTRU may compute a small data CG-RNTI as a functionof the time and frequency domain resource allocation of the selected CGand the selected PRBs on which the small data were transmitted. Forexample, a WTRU may receive RRC signalling to configure a small dataCG-RNTI for a given CG. The WTRU may discard the small data CG-RNTIafter changing to a different cell or cell group and/or after expiry ofthe CG response window.

In some cases, the WTRU may receive a small data response (SDR) duringthe CG response window. The SDR may include one or more types ofinformation. For instance, the SDR may include an uplink grant for aretransmission or a subsequent transmission. For example, the WTRU mayreceive a dynamic UL grant for the same HARQ process ID forretransmitting the small data TB. The WTRU may receive an UL grant witha different HARQ PID or the same HARQ PID with a new data indicator(NDI) toggled for the purpose of transmitting subsequent or furthersmall data. The WTRU may monitor the PDCCH, possibly for a durationmatching the configured window, after transmission or retransmission ofsmall data on a grant provided for retransmission of small data ortransmission of subsequent small data.

In some solutions, the SDR may include HARQ-ACK information relating tothe transmitted TB. The WTRU may receive an explicit HARQ-ACK, forexample, on a downlink control channel. The WTRU may determine theHARQ-ACK implicitly from the NDI value for a subsequent scheduled grantfor the same HARQ process used to transmit the small data TB. Forinstance, the WTRU may determine an ACK if the NDI is toggled for thesame HARQ process in a subsequently scheduled grant. The WTRU may alsodetermine a HARQ-ACK value based on the expiry of a timer, such as theCG response window or the CG timer, if configured. For example, the WTRUmay determine ACK if the CG response window has expired and the WTRU hasnot received a subsequent UL grant for the same HARQ process ID.

In some solutions, the SDR may include a backoff indication and backofftime. A WTRU may retransmit the small data TB on the same or a differentCG after receiving a backoff indication and waiting for a backoffperiod.

In some solutions, the SDR may include an applicability indication forone or more WTRUs, or a group or subset of WTRUs. For example, a bit maybe included part of the backoff MAC sub-PDU or in a DCI indicating thatbackoff is only applicable to WTRUs capable of small data transmissionor only applicable to WTRUs in inactive or connected modes. In anotherexample, the applicability indication may be a unique ID to indicate asubset of WTRUs, such as a small data RNTI, a CG-RNTI, or an RNTI thatcorresponds to the identity of single WTRU C-RNTI or I-RNTI.

In some solutions, the SDR may include an indication bit to signal tothe WTRU to switch to the different small data transmission method,possibly after backoff. For instance, the indication bit may signal toswitch to different CG resources, initiate a two-step or four-step RAprocedure for small data transmissions or retransmissions.

In some solutions, the SDR may include a timing advance or a timingadvance adjustment. The SDR may include an incremental timing advancedelta or an absolute timing advance value, and the WTRU may apply oradjust the signalled TA for the upcoming retransmissions or any uplinktransmission.

In some solutions, the SDR may indicate whether to apply power rampingfor a retransmission on CG. The SDR may provide an indication toretransmit a different CG resource, possibly after backoff, or the SDRmay provide an indication to retransmit the payload on the same CGresource but with a preamble, such as when the CG is also used fortransmission of the data payload of a two-step RA procedure.

In some solutions, a WTRU may determine (e.g., implicitly) that a TBtransmission was successful, or unsuccessful, upon receiving anindication (e.g. ACK) in an SDR applicable to the WTRU, or upon expiryof a CG response window without reception of applicable scheduling forthe WTRU. In some solutions, the WTRU may assume the TB transmission wasunsuccessful (e.g. NACK) upon failing to receive an SDR applicable tothe WTRU by the end of the CG response window.

In some solutions, the WTRU may apply power ramping for a retransmissionon a CG, possibly upon reception of a backoff indication. The WTRU mayapply power ramping, for example, depending on whether the same CGresource, same uplink beam, same uplink, and/or same uplink carrier wasselected. The WTRU may maintain a power ramping counter associated withsmall data transmission on CGs. The WTRU may be configured via RRCsignaling with a maximum number of transmission attempts. The WTRU mayalso be configured with a power ramping step via RRC signaling and usethat value upon ramping power. The WTRU may alternatively determine thepower ramping step based on the TB size. For example, the WTRU may scalethe configured power ramping step or select a different power rampingstep if the TBS is larger than, or smaller than, a certain threshold. Insome solutions, the WTRU may apply a prioritized/scaled backoff or powerramping if small data was transmitted and data from certain LCHs wasincluded in the TB.

Further embodiments directed to CG and resource selection are describedherein. In some solutions, a WTRU may have one or more CGs configuredfor small data transmission, possibly on different carriers and/ordifferent uplinks. The WTRU may be able to select a configured grant forsmall data transmission if one or a combination of conditions are met.For example, the condition may be based on a TBS. The WTRU may beconfigured with a TBS range per CG for the purpose of selecting a CG.The WTRU may select a CG if the amount of buffered data from LCHsapplicable for small data transmission falls within the configured TBSrange for the CG. In one example, when one or more CGs are available,the WTRU may select the CG with the smallest TBS that would fit thebuffered small data.

In some cases, the condition may be based on based on channelconditions. The WTRU may be configured with channel condition range orthreshold, such as an RSRP, pathloss, or power headroom. The WTRU mayselect a configured grant for small data transmission if the measuredchannel condition is within the configured range or less than thethreshold. In some examples, a channel condition range or threshold canbe configured collectively per uplink or per uplink carrier (i.e. forall configured grants on the same uplink or the same uplink carrier). AWTRU may combine this selection criterion with the TB size; for example,the WTRU may select CG 1 if the TB exceeds a threshold for CG1 and ifpathloss is less than a threshold, or if RSRP exceeds a threshold.

In some cases, the condition may be based on one or more timing advance(TA) values. In one example, the WTRU can be configured per cell with arange of TA values for which the WTRU is allowed to use configuredgrants or an uplink carrier for small data transmission in idle orinactive modes. The WTRU may maintain the TA value last used upontransitioning from connected mode. With such configuration, the WTRU maytransmit small data on the configured CGs if the TA is within theapplicable range, or the WTRU may use a RA-based small datatransmission. The WTRU may further determine that a CG is applicable forsmall data transmissions if the maintained TA value has not changed forconfigured period of time. In another example, small cells may lack ULTA issues, so there may be no need for a timing advance, but powerramping could be used on PUSCH, for example, for HARQ retransmissions.In some methods, the WTRU may select a CG for transmission only afterhaving received a TA command in INACTIVE state.

For example, a WTRU may maintain a TA timer for the maintenance of theTA (e.g., in inactive/idle states) and/or for determining whether a CGcan be used for small data transmission. The WTRU may start, or restart,the TA timer upon receiving a TA command (e.g., in a MAC CE), upontransitioning into inactive state, and/or upon receiving a TA command aspart of a RA procedure (e.g., in Msg2 or MsgB). The WTRU may assume theCG to be valid for small data transmission while the TA timer is running(e.g., not expired). Upon expiry of the TA timer, the WTRU may use aRACH resource for small data transfer. E

As another example, the WTRU may extend the maintenance of the TA timerto inactive and/or idle modes. The WTRU may start, or restart, the TAtimer upon any of receiving a TA command (e.g., in a MAC CE),transitioning into the inactive state, and/or receiving a TA command aspart of a RA procedure (e.g., in Msg2 or MsgB). The WTRU may assume a CGto be valid for small data transmission while the TA timer is running(e.g., non-expired),

In some cases, the condition may be based on the selected uplink, forexample, whether a normal uplink (NUL) or a supplementary uplink (SUL)is selected. The WTRU may only consider CGs in the active BWP andselected uplink. The WTRU may perform an uplink selection method priorto CG selection, for example, based on the measured RSRP. The WTRU maythen select CGs configured on the selected uplink carrier, active uplinkcarrier, and/or active BWP. In some cases, the condition may be based onmeasured channel conditions. Measured channel conditions may beexpressed in terms of an S-measure, a CRE region, and/or L3 channelmeasurements. For example, the WTRU may select a given CG resource forsmall data transmission if a certain RRM synchronization criterion isdetermined, such as if one or more RRM measurements are above aconfigured threshold or within a range. The WTRU may consider the CGresource as not applicable for small data transmission otherwise, suchas if the synchronization criterion is not satisfied.

In some cases, the condition may be based on the LCH on which data isbuffered/to be transmitted. For example, the WTRU may select a certainconfigured grant in inactive state only if the LCH with buffered smalldata is configured with an LCP restriction allowing data transmission onthat grant. Each LCH may be configured with a list of applicable CGs fortransmission in inactive or idle states.

In some cases, the condition may be based on priority (e.g. LCHpriority, access class priority, upper layer access identity, QoSrequirements configured for the associated DRBs). The WTRU may use a CGfor small data transmission only if data is associated with certainpriority or access identity. CGs may be configured by RRC with the listof applicable priorities, QoS requirements, and/or access identities.

In some cases, the condition may be based on whether SRB data is to betransmitted using part of the small data PDU. For example, the WTRU mayuse a CG for transmission only for DRBs (or a subset of DRBs).

Various procedural aspects of small data transmission are describedherein. In some cases, such as when a WTRU is mobile, small datatransmissions may be performed with or without anchor relocation. If aWTRU moves around while in idle or inactive mode and changes coveragearea (RAN paging area), the WTRU may transmit a packet in a new coveragearea, possibly if certain conditions are met. The WTRU may transmit datato the target nodeB if the WTRU context is kept or maintained at thetarget nodeB. The WTRU may trigger a RA procedure transmit data if thecontext is not known at the target nodeB. The WTRU may include suchResume ID, which may provide the AS context to the target nodeB, in suchRA.

Depending on the circumstances, a small data format may vary, and a WTRUmay include one of several types of information in a small data PDU,sub-PDU, or MAC CE. For example, the WTRU may include data from one ormore LCHs. The WTRU may be configured with a subset of LCHs that areapplicable for small data transmission. The WTRU may include the WTRU'sresumeID, which may enable the network to transition the WTRU toconnected mode (e.g., RRC resume request). The WTRU may also include theWTRU's I-RNTI or C-RNTI.

In some cases, the WTRU may include a BSR or amount of remaining smalldata, or a “small data BSR.” This may include, for instance, data forsmall data LCHs, which may be LCHs configured as applicable for smalldata transmissions. The BS level may be estimated or indicated as apointer to a predefined range of bits index.

In some cases, a WTRU may include an indication as to whether subsequentdata is to follow. For example, the WTRU may include a bit indication ifbuffered small data is greater than zero or greater than a configuredthreshold after TB construction, possibly only counting buffered bitsfrom LCHs configured as applicable for small data transmission.

In some cases, a WTRU may include scheduling information, which mayfurther include CSI reports or power headroom (PHR). The WTRU mayinclude such information in certain conditions, such as when a PHR orCSI report is triggered or the delta since the last report is largerthan a certain threshold.

In some cases, a WTRU may include a selected preamble (RAPID), which maybe helpful in decoding collisions at the received if a 1-1 mappingbetween the PRACH resource and the PUSCH resource does not exist. Insome cases, the WTRU may include an acknowledgment (e.g., HARQ-ACK) fora previously received TB. In some cases, a WTRU may include a HARQprocess ID associated with or used to store the small data TB.

In some cases, a WTRU may include an RRC message (e.g., RRC resume),such as when the context is not known at a target (e.g., a serving gNB).The WTRU may include the RRC message as a function of a resource used.For example, a WTRU may include an RRC message upon condition thatRACH-based small data resources are used and not include it uponcondition that CG resources are used to transmit the small data PDU, AWTRU may exclude the RRC message if the serving cell hasn't changedsince the WTRU has acquired the CG configuration, A WTRU may exclude theRRC message if the WTRU has already sent an RRC resume request and theserving cell has not changed (e.g., since the RRC resume request wassent).

In some embodiments, a WTRU may be configured for small datatransmission via RRC or broadcast signalling with one or a combinationof types of information. For example, a WTRU may be configured withdedicated (two-step, four-step, or CG) resources, which the WTRU maymaintain when entering inactive and/or idle mode. The WTRU may beconfigured with a subset of PRACH and/or PUSCH resources applicable forsmall data transfer. The WTRU may configured with an indication whetherHARQ feedback is used, for which a WTRU can be configured per resourceor UL transmission method (two-step, four-step, or CG).

The WTRU may be configured with small data applicability per LCH, DRB,LCG, or QoS flow configuration. For example, when small datatransmission is applicable, the WTRU may restrict small datatransmission to a subset of LCHs. In some cases, this may be an LCHrestriction in LCP for instance. The WTRU may be configured with a smalldata LCP restriction for a subset of LCHs, whereby the WTRU onlyincludes data from those LCHs for resources applicable for small datatransfer. In some cases, certain DRBs may be suspended in inactive oridle mode. The WTRU may be configured via RRC signaling per DRB withinformation whether the DRB is maintained or suspended in idle and/orinactive mode.

Conditions for successfully performing small data transmission procedureare described herein. In some embodiments, the WTRU may consider a smalldata transfer procedure successful, or unsuccessful, possibly per HARQprocess applicable for small data, if at least one of several conditionsoccur. Such conditions may include reception of MsgB, possibly withI-RNTI or RNTI provided in MsgA. The RNTI can by scrambled in the PDCCHthat scheduled MsgB or provided in the contents of MsgB.

Conditions for successful small data transfer may include reception ofMsg4, possibly with I-RNTI or RNTI provided in MsgA or Msg3. The RNTIcan by scrambled in the PDCCH that scheduled MsgB or provided in thecontents of Msg4. Conditions for successful small data transfer mayinclude delivering HARQ-ACK with ACK for MsgB. The WTRU may consider thesmall data transfer procedure successful after deliver a HARQ-ACK valuefor the small data PDU transmitted or received, possibly with thecondition that the value is equal to “ACK”. Conditions for successfulsmall data transfer may include reception of a TA command MAC CE.Conditions for successful small data transfer may include, for example,the WTRU determining it has no further small data to transmit from thebuffer status, based on not sending a request to transmit furthersubsequent small data, or not receiving an indication from the networkfor small data transfer. Conditions for successful small data transfermay include reception of HARQ-ACK for transmitted small data orreception of a PDCCH transmission on a certain CORESET or search space.A WTRU may consider the procedure successful upon determining an ACK forthe corresponding HARQ process. Conditions for successful small datatransfer may include expiry of a timer. A WTRU may consider theprocedure successful, or unsuccessful, upon expiry of a timer. In someexamples, the WTRU may consider the procedure successful upon notreceiving a retransmission grant or a grant for subsequent transmissionwithin a time duration within the transmission of the small data PDU(initial or subsequent). The WTRU may maintain a timer for such purpose(e.g., a small data retransmission timer or small data failurehandling), and may reset the timer each time small data is transmitted,upon reception of a fallback RAR, or upon expiry of the contentionresolution timer without receiving a Msg4. The WTRU may stop the timerupon determining a ACK is received. The WTRU may start the timer (e.g.,only) for the first transmission attempt for a small data packet and/orwithout consideration to retransmissions and/or subsequenttransmissions/segments.

Upon condition that a small data transfer procedure has failed and/orupon condition that the timer has expired, the WTRU may performprocedures and/or actions related to any of cell re-establishment, RRCre-establishment, DRB suspension, transitioning to IDLE mode and/orinitiating a new RACH procedure (e.g., on a different cell and/or BWP).For example, the WTRU may transmit an RRC connection resume request, aRRC establishment request, and/or RRC reestablishment request. While thetimer is running, the WTRU may remain in INACTIVE state. In some cases,the WTRU may remain in the INACTIVE state even if another event thattriggers the WTRU to go to IDLE mode may have been triggered (e.g., cellreselection). The WTRU may maintain any unacknowledged small data in thebuffer while the timer is running. In some cases, the timer can bemaintained per MAC entity, per DRB, or per HARQ process.

A small data transfer procedure may be considered pending by the WTRUuntil it is successful or cancelled. The WTRU may monitor certain PDCCHresources or search spaces while a small data transfer procedure ispending. The WTRU may perform certain L1, L3, CSI, and/or RRMmeasurements while a small data procedure is pending.

Embodiments directed to channel measurement and reporting in IDLE andINACTIVE states (e.g., CSI reporting) are described herein. In IDLE andINACTIVE states, a WTRU may monitor SSBs from the serving cell and fromneighbouring cells. The WTRU may perform SS-RSRP and SS-RSRQmeasurements on the serving cell to determine whether a cell fulfillsthe cell reselection criteria. If a WTRU is sending small data, a WTRUmay also want to send an indication of channel quality (e.g. CSI) thatmay be used for link adaptation. In some scenarios, however, there maybe no method for a WTRU to send channel quality reports in IDLE andINACTIVE states. In the following, a CSI report may include one ormultiple types of feedback related to channel quality measurement suchas SNR, SINR, RSRP, RI, CQI, MCS.

In some solutions, a WTRU may determine a CSI value and may include itas part of a small data transmission. The CSI may be reported, forexample, via a UCI report, via a MAC-CE, or in the small data PDU or aPDU header or subheader. A WTRU reporting the CSI via a UCI report maysend its small data using a PUSCH, and a WTRU may multiplex a UCI reportin a PUSCH message. A WTRU may determine the resource elements (REs) forthe UCI report based on a configuration for small data PUSCHtransmissions. The WTRU may determine the configuration based onexisting rules for multiplexing UCI in PUSCH, or a new configuration maybe determined for PUSCH used in small data. In some solutions, the WTRUmay reuse an existing UCI format. Alternatively, a special UCI formatmay be used for small data transmission with reduced overhead.

In some methods, a WTRU may report a MAC-CE used in IDLE or INACTIVEwhich may contain a CSI report. For example, the MAC-CE for recommendedbit rate query may be used by the WTRU. In some embodiments, a MAC-CEmay be with a new format defined for small data transmission which mayinclude a CSI report similar to CONNECTED state (e.g. CQI, RI, and/orMCS).

In some embodiments, a WTRU may determine to send a CSI report based ona configuration by a nodeB (e.g., a gNB). The small data transmissionformat may be configured with or without CSI reporting embedded.Alternatively, a WTRU may determine the small data format and maydetermine whether to include a CSI report or not. The WTRU may determineto report CSI based on one or more of several factors as describedbelow.

For instance, the determination may be based on whether the WTRU hasmore data available to send in its buffer. For example, a WTRU mayinclude a report if the WTRU determines that subsequent transmissionsare required, or only if a subsequent transmission contains new data.The determination may be based on the WTRU's buffer status. A WTRU maydetermine to include CSI report if its buffer content size is above athreshold and/or based on having data buffered from LCH(s) applicablefor small data transmission.

The determination may be based on the WTRU's channel conditionmeasurements. A WTRU may determine to include a CSI report if thechannel measurements (e.g. RSRP) are above or below a threshold. WTRUmay include a CSI report only after measuring a configured subset ofCSI-RS resource set(s) and/or SSB(s).

The determination may be based on the WTRU's time since last datatransmission. A WTRU may determine to include a CSI report if the timesince it last performed an UL data transmission or DL data reception islarger than a threshold. Alternatively or additionally, a WTRU maytrigger a CSI report whenever it receives DL data, possibly with acertain priority or from a certain LCH or DRB.

The determination may be made based on a paging message. WTRU may reportCSI after reception of paging. A WTRU may receive a RAN paging or CNpaging message, and a WTRU may determine the resources to include theCSI report in one or more of a PUCCH following the paging; a PUSCHresource associated with a random access triggered by the paging; asemi-statically configured PUSCH resource; or a RACH procedure. A WTRUmay receive a PDCCH order to initiate a RACH procedure and a WTRU maytrigger the transmission of a CSI report. A WTRU may determine theresources for the CSI report to be on a PUCCH, or on a PUSCH. The WTRUmay determine the PUSCH resources as explicitly indicated in the PDCCHorder. The WTRU may determine the PUSCH resources as preconfigured andlinked to a PDCCH order. A WTRU may for example determine to use a setof resources that may be configured every T seconds following a PDCCHorder. In some embodiments, the WTRU may determine the PUSCH as reservedresources within RACH configuration. For example, PRBs may be reservedfollowing a PDCCH order, and the resources may be linked to preambles.In some embodiments, a WTRU may determine the resources based on thepreamble.

The WTRU may determine to report CSI based on a traffic type (e.g.URLLC, eMBB). The WTRU may report CSI if it has buffered small data fortransmission or reception for a certain LCH, LCG, DRB, and/or QoS flow.

The WTRU may determine to report CSI upon reception of an indication ofDCI or scheduling of PDSCH in INACTIVE mode. The indication may beprovided to the WTRU as a configured or predefined properly of the PDSCHscheduling.

The WTRU may determine to report CSI based on a slot format indicator. AWTRU may determine based on the SFI that some slots may require a CSIreport and others not. A WTRU may include the report if the data is sentin a slot flagged for reporting.

Embodiments directed to various types of measurements are describedherein. In some embodiments, a WTRU may or may not have RS available forCSI measurements. For example, a WTRU may not be monitoring CSI-RS inIDLE or INACTIVE mode. Then in one solution, a WTRU may use the latestmeasurement performed in CONNECTED state if it was done less than Tseconds where T may be a configured threshold. Alternatively, a WTRU mayperform measurements for spatial filter selection prior to selecting aresource for small data transmission. A WTRU may determine to use thesemeasurements as part of the CSI report.

In some embodiments, a WTRU may determine other measurements using SSBsand a WTRU may use them to determine a CSI. In one solution, a WTRU mayinclude a CSI measurement based on available measurements in IDLE orINACTIVE such as SS-RSRP, SS-RSRQ. Alternatively, a WTRU may determine abitstring mapped to the channel measurement values and the WTRU mayreport the bitstring. The bitstring may represent an MCS value based onIDLE or INACTIVE channel measurements. For example, a mapping table maybe configured between measured SS-RSRP/SS-RSRQ values and MCS values. AWTRU may use the table to determine the MCS value and a WTRU may includethe index of the MCS value in the report.

Alternatively, the channel measurement may be mapped to a range ofvalues and the range may be reported. For example, measurement valuesfalling between X0 and X1 dB may be mapped to bit 0, between X1 and X2to bit 1, for example.

FIG. 2 is a representative procedure that may be implemented by a WTRU102 to transmit a small data payload using a SDT resource. As shown inFIG. 2 , a WTRU 102 may implement a procedure 200 to transmit SDT datausing a SDT resource. At 210, the WTRU 102 may receive informationindicating a configuration of one or more small data transmission (SDT)resources. At 220, the WTRU 102 may receive information indicating oneor more data radio bearers (DRBs) which support SDT. At 230, the WTRU102 may receive information indicating an inactive radio networktemporary identifier (I-RNTI) (e.g., to indicate to transition toinactive mode). In certain representative embodiments, any of 210, 220and/or 230 may be combined and/or reordered. At 240, the WTRU 102 maydetermine whether uplink (UL) SDT data for transmission is present in abuffer of the WTRU 102. At 250, on condition that (1) the UL SDT data isdetermined to be present in the buffer, (2) a size of the UL SDT datapresent in the buffer is less than a first threshold, and (3) the UL SDTdata present in the buffer is for the one or more DRBs which supportSDT, the WTRU 102 may, after receiving the information indicating theI-RNTI, transmit at least a portion of the UL SDT data present in thebuffer using a SDT resource from among the one or more SDT resources.The SDT resource may, for example, be any of an UL grant provided inMsg2, a Msg3 PUSCH resource, an UL grant provided in Msg4, a MsgA PUSCHresource, an UL grant provided in MsgB, a CFRA resource, or a CGresource as described herein.

In certain representative embodiments, the WTRU 102 may, on furthercondition that the size of the UL SDT data for transmission present inthe buffer is greater than a size of the SDT resource, the transmissionat 250 may include transmitting information indicating the size of theUL SDT present in the buffer using the same SDT resource (e.g., as theUL SDT data). As an example, the information indicating the amount of ULSDT present in the buffer may be included in a small data buffer statusreport (BSR).

In certain representative embodiments, the WTRU 102 may consider whetherthe amount of all the UL SDT data present in the buffer is less than thefirst threshold and whether all the UL SDT data present in the buffer isfor the one or more DRBs which support SDT at 240. In otherrepresentative embodiments, the WTRU 102 may compute the amount ofbuffered small data per the other examples as described herein.

In certain representative embodiments, the WTRU 102 may measure a RSRPof one or more RSs. For example, the transmitting of the at least theportion of the UL SDT data present in the buffer using the SDT resourcemay be further conditioned on (4) the measured RSRP being greater thanor equal to a second threshold at 250.

In certain representative embodiments, the WTRU 102 may perform a RAprocedure (e.g., two-step or four-step RA) after receiving theinformation indicating the I-RNTI. The SDT resource used fortransmission at 250 may be a RACH resource, such as a Msg3 PUSCHresource or another resource as described herein.

FIG. 3 is a representative procedure that may be implemented by a WTRU102 to transmit a small data payload using a SDT resource. As shown inFIG. 3 , a WTRU 102 may implement a procedure 200 to transmit SDT datausing a SDT resource. At 310, the WTRU 102 may receive informationindicating a configuration of one or more small data transmission (SDT)resources. At 320, the WTRU 102 may receive information indicating oneor more data radio bearers (DRBs) which support SDT. At 330, the WTRU102 may receive information indicating an inactive radio networktemporary identifier (I-RNTI) (e.g., to indicate to transition toinactive mode). In certain representative embodiments, any of 310, 320and/or 330 may be combined and/or reordered. At 340, the WTRU 102 maydetermine whether uplink (UL) SDT data for transmission is present in abuffer of the WTRU 102. At 250, on condition that (1) the UL SDT data isdetermined to be present in the buffer, (2) a size of the UL SDT datapresent in the buffer is less than a first threshold, and (3) the UL SDTdata present in the buffer is for the one or more DRBs which supportSDT, the WTRU 102 may, after receiving the information indicating theI-RNTI, transmit the UL SDT data present in the buffer using a SDTresource from among the one or more SDT resources. The SDT resource may,for example, be any of an UL grant provided in Msg2, a Msg3 PUSCHresource, an UL grant provided in Msg4, a MsgA PUSCH resource, an ULgrant provided in MsgB, a CFRA resource, or a CG resource as describedherein.

In certain representative embodiments, the WTRU 102 may consider whetherthe amount of all the UL SDT data present in the buffer is less than thefirst threshold and whether all the UL SDT data present in the buffer isfor the one or more DRBs which support SDT at 340. In otherrepresentative embodiments, the WTRU 102 may compute the amount ofbuffered small data per the other examples as described herein.

In certain representative embodiments, the WTRU 102 may measure a RSRPof one or more RSs. For example, the transmitting of the at least theportion of the UL SDT data present in the buffer using the SDT resourcemay be further conditioned on (4) the measured RSRP being greater thanor equal to a second threshold at 350.

In certain representative embodiments, the WTRU 102 may perform a RAprocedure (e.g., two-step or four-step RA) after receiving theinformation indicating the I-RNTI. The SDT resource used fortransmission at 250 may be a RACH resource, such as a Msg3 PUSCHresource or another resource as described herein.

In certain representative embodiments, the WTRU 102 may, after thetransmitting of the at least the portion of the UL SDT data present inthe buffer using the SDT resource at 250 or 350, send a request toresume a RRC connection to a RAN.

FIG. 4 . is a representative procedure that may be implemented by a WTRUusing a SDT resource to determine whether or not to transition toconnected mode. As shown in FIG. 4 , a WTRU 102 may implement aprocedure 400 to transition to connected mode (e.g., from inactivemode). At 410, the WTRU 102 may receive information indicating aconfiguration of one or more small data transmission (SDT) resources. At420, the WTRU 102 may receive information indicating one or more dataradio bearers (DRBs) which support SDT. At 430, the WTRU 102 may receiveinformation indicating an inactive radio network temporary identifier(I-RNTI) (e.g., to indicate to transition to inactive mode). In certainrepresentative embodiments, any of 410, 420 and/or 4330 may be combinedand/or reordered. At 440, the WTRU 102 may determine whether uplink (UL)SDT data for transmission is present in a buffer of the WTRU 102. At450, the WTRU 102 may, on condition that (1) at least a portion of theUL SDT data present in the buffer is for a DRB which does not supportSDT, or (2) the UL SDT data present in the buffer is for the one or moreDRBs which support SDT and a size of the UL SDT data present in thebuffer is greater than or equal to a first threshold, send a request toresume a radio resource control (RRC) connection to a radio accessnetwork (RAN), the request to resume the RRC connection may include theinformation indicating the I-RNTI.

In certain representative embodiments, the WTRU 102 may consider whetherthe amount of all the UL SDT data present in the buffer is less than thefirst threshold and whether all the UL SDT data present in the buffer isfor the one or more DRBs which support SDT at 340. In otherrepresentative embodiments, the WTRU 102 may compute the amount ofbuffered small data per the other examples as described herein.

In certain representative embodiments, the WTRU 102 may measure a RSRPof one or more RSs. For example, the sending of the request to resumethe RRC connection may be further conditioned on (4) the measured RSRPbeing less than a second threshold at 450.

FIG. 5 is a representative procedure that may be implemented by a WTRU102 to transmit a small data payload using a SDT resource. As shown inFIG. 5 , a WTRU 102 may implement a procedure 200 to transmit SDT datausing a SDT resource. At 510, the WTRU 102 may receive informationindicating a configuration of one or more small data transmission (SDT)resources. At 520, the WTRU 102 may receive information indicating oneor more data radio bearers (DRBs) which support SDT. At 530, the WTRU102 may receive information indicating an inactive radio networktemporary identifier (I-RNTI) (e.g., to indicate to transition toinactive mode). In certain representative embodiments, any of 510, 520and/or 530 may be combined and/or reordered. At 540, the WTRU 102 maymeasure a RSRP of one or more RSs. At 550, the WTRU 102 may determinewhether uplink (UL) SDT data for transmission is present in a buffer ofthe WTRU 102. At 560, on condition that (1) the UL SDT data isdetermined to be present in the buffer, (2) a size of the UL SDT datapresent in the buffer is less than a first threshold, (3) the UL SDTdata present in the buffer is for the one or more DRBs which supportSDT, and (4) the measured RSRP is greater than or equal to a secondthreshold, the WTRU 102 may, after receiving the information indicatingthe I-RNTI, transmit at least a portion of the UL SDT data present inthe buffer using a SDT resource from among the one or more SDTresources. The SDT resource may, for example, be any of an UL grantprovided in Msg2, a Msg3 PUSCH resource, an UL grant provided in Msg4, aMsgA PUSCH resource, an UL grant provided in MsgB, a CFRA resource, or aCG resource as described herein.

FIG. 6 is a representative procedure that may be implemented by a WTRUusing a SDT resource to determine whether or not to transition toconnected mode. As shown in FIG. 6 , a WTRU 102 may implement aprocedure 600 to transition to connected mode. At 610, the WTRU 102 mayreceive information indicating a configuration of one or more small datatransmission (SDT) resources. At 620, the WTRU 102 may receiveinformation indicating one or more data radio bearers (DRBs) whichsupport SDT. At 630, the WTRU 102 may receive information indicating aninactive radio network temporary identifier (I-RNTI) (e.g., to indicateto transition to inactive mode). In certain representative embodiments,any of 610, 620 and/or 630 may be combined and/or reordered. At 640, theWTRU 102 may measure a RSRP of one or more RSs. At 650, on conditionthat (1) at least a portion of the UL SDT data present in the buffer isfor a DRB which does not support SDT, or (2) the UL SDT data present inthe buffer is for the one or more DRBs which support SDT and a size ofthe UL SDT data present in the buffer is greater than or equal to afirst threshold, or (4) the measured RSRP is less than a secondthreshold, the WTRU 102 may send a request to resume a radio resourcecontrol (RRC) connection to a radio access network (RAN). The request toresume the RRC connection may include the information indicating theI-RNTI.

FIG. 7 is a representative procedure that may be implemented by a basestation to receive a small data payload using a SDT resource from a WTRUin inactive mode. As shown in FIG. 7 , a base station (e.g., gNB 180)may implement a procedure to receive a SDT payload (e.g., from a WTRU102). At 710, the gNB 180 may send information indicating aconfiguration of one or more small data transmission (SDT) resources. At720, the gNB 180 may send information indicating one or more data radiobearers (DRBs) which support SDT. At 730, the gNB 180 may sendinformation indicating an inactive radio network temporary identifier(I-RNTI) (e.g., to indicate to transition to inactive mode). In certainrepresentative embodiments, any of 710, 720 and/or 730 may be combinedand/or reordered. At 740, the gNB 180 may, after sending the informationindicating the I-RNTI, receive at least a portion of UL SDT data presentin a buffer of a WTRU 102 using a SDT resource from among the one ormore SDT resources. The SDT resource may, for example, be any of an ULgrant provided in Msg2, a Msg3 PUSCH resource, an UL grant provided inMsg4, a MsgA PUSCH resource, an UL grant provided in MsgB, a CFRAresource, or a CG resource as described herein.

FIG. 8 is a representative procedure that may be implemented by a basestation to transition a WTRU to connected mode. As shown in FIG. 8 , abase station (e.g., gNB 180) may implement a procedure 800 to transition(e.g., begin to transition) a WTRU 102 from inactive mode to connectedmode. At 810, the gNB 180 may send information indicating aconfiguration of one or more small data transmission (SDT) resources. At820, the gNB 180 may send information indicating one or more data radiobearers (DRBs) which support SDT. At 830, the gNB 180 may sendinformation indicating an inactive radio network temporary identifier(I-RNTI) (e.g., to indicate to transition to inactive mode). In certainrepresentative embodiments, any of 810, 820 and/or 830 may be combinedand/or reordered. At 840, the gNB 180 may after sending the informationindicating the I-RNTI, receive a request to resume a radio resourcecontrol (RRC) connection to a radio access network (RAN). The request toresume the RRC connection may include the information indicating theI-RNTI.

FIG. 9 is a representative procedure that may be implemented by a WTRUto determine whether or not to transition to connected mode. As shown inFIG. 9 , a WTRU 102 may implement a procedure 900 to transition (e.g.,begin to transition) from inactive mode to connected mode. At 910, theWTRU 102 may receive the WTRU 102 may receive information indicating aconfiguration of one or more small data transmission (SDT) resources. At920, the WTRU 102 may receive information indicating a configuration ofone or more small data transmission (SDT) resources. At 930, the WTRU102 may receive information indicating an inactive radio networktemporary identifier (I-RNTI) (e.g., to indicate to transition toinactive mode). In certain representative embodiments, any of 910, 920and/or 930 may be combined and/or reordered. The WTRU 102 may, afterreceiving the information indicating the I-RNTI, transmit at least aportion of UL SDT data present in a buffer of the WTRU using a SDTresource from among the SDT resources. The SDT resource may, forexample, be any of an UL grant provided in Msg2, a Msg3 PUSCH resource,an UL grant provided in Msg4, a MsgA PUSCH resource, an UL grantprovided in MsgB, a CFRA resource, or a CG resource as described herein.At 950, the WTRU 102 may determine whether or not the transmission ofthe at least the portion of the UL SDT data has been successfullyreceived. On condition that the transmission of the at least the portionof the UL SDT data is determined not to have been successfully receivedfor a configured or predetermined amount of time from the transmissionof the at least the portion of the UL SDT data, the WTRU 102 may send arequest to resume or re-establish a RRC connection to a RAN at 960.

FIG. 10 is a representative procedure that may be implemented by a basestation to transition a WTRU to connected mode. As shown in FIG. 10 , abase station (e.g., gNB 180) may implement a procedure 1000 totransition (e.g., begin to transition) a WTRU 102 from inactive mode toconnected mode. At 1010, the gNB 180 may send information indicating aconfiguration of one or more small data transmission (SDT) resources. At1020, the gNB 180 may send information indicating one or more data radiobearers (DRBs) which support SDT. At 1030, the gNB 180 may sendinformation indicating an inactive radio network temporary identifier(I-RNTI) (e.g., to indicate to transition to inactive mode). In certainrepresentative embodiments, any of 1101, 1020 and/or 1030 may becombined and/or reordered. At 1040, the gNB 180 may determine whether anUL SDT data transmission is received or not using one of the SDTresources. For example, any of the examples described herein may be usedto determine whether or not the UL SDT data payload has been received(e.g., successfully or not). At 1050, the gNB 180 may, on condition thatat least a portion of the UL SDT data transmission has not beenreceived, send information indicating that at least the portion of theUL SDT data transmission has not been received. At 1060, the gNB 180 mayreceive (e.g., from the WTRU 102) a request to resume or re-establish aRRC connection.

FIG. 11 is a representative procedure that may be implemented by a WTRUto transmit a small data payload using a contention-free random access(CFRA) resource. As shown in FIG. 11 , a WTRU 102 may implement aprocedure 1100 to transmit a small data payload using a CFRA resource ininactive mode. At 1110, the WTRU 102 may receive information indicatinga configuration of one or more small data transmission (SDT) resources.At 1120, the WTRU 102 may receive information indicating one or moredata radio bearers (DRBs) which support SDT. At 1130, the WTRU 102 mayreceive information indicating an inactive radio network temporaryidentifier (I-RNTI) (e.g., to indicate to transition to inactive mode).In certain representative embodiments, any of 1110, 1120 and/or 1130 maybe combined and/or reordered. At 1140, the WTRU 102 may determinewhether uplink (UL) SDT data for transmission is present in a buffer ofthe WTRU 102. At 1150, the WTRU 102 may, after receiving the informationindicating the I-RNTI, transmit at least a portion of the UL SDT datapresent in the buffer using a CFRA resource from among the one or moreSDT resources based on any of (1) quality of service (QoS) informationassociated with the UL SDT data present in the buffer and/or (2) ameasured channel condition. For example, the QoS information may includea latency requirement which is associated with the UL SDT data presentin the buffer. As another example, the measured channel condition mayinclude any of an RSRP, a RSRQ and/or a SINR. At 1140, the CFRA resourcemay be used, for example, on further condition that the latencyrequirement is less than a first threshold and/or that measured channelcondition is greater than a second threshold.

FIG. 12 is a representative procedure that may be implemented by a basestation to receive a small data payload using a contention-free randomaccess (CFRA) resource. As shown in FIG. 12 , a base station (e.g., gNB180) may implement a procedure 1200 to receive a small data payloadusing a contention-free random access (CFRA) resource. At 1210, the gNB180 may send information indicating a configuration of one or more smalldata transmission (SDT) resources. At 1220, the gNB 180 may sendinformation indicating one or more data radio bearers (DRBs) whichsupport SDT. At 1230, the gNB 180 may send information indicating aninactive radio network temporary identifier (I-RNTI) (e.g., to indicateto transition to inactive mode). In certain representative embodiments,any of 1210, 1220 and/or 1230 may be combined and/or reordered. The oneor more SDT resources may include one or more CFRA resources asdescribed herein. At 1240, the base station may, after sending theinformation indicating the I-RNTI, receive an UL SDT data transmissionusing one of the CFRA resources at 1240.

In certain representative embodiments, the procedures 200 to 1200 shownin FIGS. 2 to 12 may be performed during a RA procedure (e.g., two-stepor four-step RA), such as after transitioning to inactive mode asdescribed herein. For example, one or more SDT resources may be providedin Msg2 or Msg4 of a four-step RA procedure or may be provided in MsgBof a two-step RA procedure as described herein. As another example, theWTRU 102 may use a CG resource as a SDT resource to transmit a SDTpayload as described herein. In certain representative embodiments, theWTRU 102 may transmit UL SDT data using a SDT resource while in inactivemode and upon determining that certain condition have been met asdescribed herein. In other representative embodiments, the WTRU 102 maysend a request to resume (or re-establish) a RRC connection upondetermining that certain other conditions have been met as describedherein.

In certain representative embodiments, a method for resource-efficienttransmission may include operating in one of an idle mode or an inactivemode, and transmitting, in response to one of a random access (RA)message or a configured grant (CG), a small data transmission over anuplink channel while in one of the idle mode or the inactive mode.

In certain representative embodiments, the method for resource-efficienttransmission may include, prior to transmitting the small datatransmission over the uplink channel, transitioning from the idle modeor the inactive mode to a connected mode in response to any of areceived configuration, a measurement event, a received datatransmission, an amount of small data to be transmitted, and/or upondetermining a payload characteristic of the small data for transmission.

In certain representative embodiments, the method for resource-efficienttransmission may include determining the amount of small data in abuffer based on a number of bits in the buffer for any of a dedicatedradio bearer, a logical channel, and/or a time period.

In certain representative embodiments, the method for resource-efficienttransmission may include determining the amount of small data in abuffer to be transmitted associated with one or more protocol layers.

In certain representative embodiments, the method for resource-efficienttransmission may include determining the amount of small data to betransmitted as a difference from a previous reported small data amount.

In certain representative embodiments, the method for resource-efficienttransmission may include transmitting a small data volume reportincluding an amount of small data to be transmitted. For example, thesmall data volume report may be included in any of a media accesscontrol (MAC) control element (CE), a MAC subheader, or a radio resourcecontrol (RRC) message.

In certain representative embodiments, the RA message is received duringone of a two-step RA procedure or a four-step RA procedure.

In certain representative embodiments, the method for resource-efficienttransmission may include determining resources for transmitting thesmall data transmission based on a received signal or based on one ormore conditions.

In certain representative embodiments, the method for resource-efficienttransmission may include determining whether the small data transmissionwas successfully received based on any of a received message, a HybridAcknowledgment Repeat Request (HARQ) acknowledgement, an implicitindication, a layer 2 command, or expiration of a timer.

In certain representative embodiments, the method for resource-efficienttransmission may include retransmitting, on a condition the small datatransmission was not received, the small data transmission.

In certain representative embodiments, the method for resource-efficienttransmission may include retransmitting, upon condition that the smalldata transmission was determined to not have been successfully received,of small data using different resources than those used for the smalldata transmission over the uplink channel.

In certain representative embodiments, the timer may be associated withany of a respective media access control entity, a respective dedicatedradio bearer, or a respective HARQ process.

In certain representative embodiments, the transmitting of the smalldata transmission further includes segmenting a small data packet into aplurality of small data packets and transmitting the small data packetsin a plurality of transmission opportunities.

In certain representative embodiments, the method for resource-efficienttransmission may include receiving a configuration for contention freeresources and selecting, based on one or more criteria, a subset of thecontention free resources for transmitting the small data transmission.

In certain representative embodiments, the method for resource-efficienttransmission may include receiving an indication to suspend, resume ortoggle small data transmission using at least a part of the contentionfree resources, wherein the indication is included in any of downlinkcontrol information (DCI), a media access control (MAC) control element,a downlink transmission, a layer 1 (L1) payload, or a layer 2 (L2)payload.

In certain representative embodiments, the method for resource-efficienttransmission may include suspending a small data transmission procedurefor at least a part of the contention free resources; and afterexpiration of a timer, resuming the small data transmission procedureusing the contention free resources.

In certain representative embodiments, the method for resource-efficienttransmission may include receiving a configuration with a set of HybridAcknowledgment Repeat Request (HARQ) processes, and determining to useat least one of the HARQ processes for the small data transmission.

In certain representative embodiments, the method for resource-efficienttransmission may include operating in at least one of an IDLE orINACTIVE state, performing channel quality measurements, andtransmitting the measured channel quality while remaining in the atleast one of the IDLE or INACTIVE state.

In certain representative embodiments, a wireless transmit/receive unit(WTRU) may be configured to perform at least part of the methods forresource-efficient transmission as described herein.

In certain representative embodiments, a system, which includes atransmitter and a receiver, may be configured to perform at least partof the methods for resource-efficient transmission as described herein.

In certain representative embodiments, a processor may be configured toperform at least part of the methods for resource-efficient transmissionas described herein. In certain representative embodiments, a networkelement may be configured to perform at least part of the methods forresource-efficient transmission as described herein. In certainrepresentative embodiments, a base station may be configured to performat least part of the methods for resource-efficient transmission asdescribed herein. In certain representative embodiments, an integratedcircuit may be configured to perform at least part of the methods forresource-efficient transmission as described herein. In certainrepresentative embodiments, a computing device may be configured toperform at least part of the methods for resource-efficient transmissionas described herein. In certain representative embodiments, anon-transitory computer readable medium may store instructions that,when executed by a processor, cause the processor to perform at leastpart of the methods for resource-efficient transmission as describedherein.

Although features and elements are provided above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. The present disclosure is not to be limitedin terms of the particular embodiments described in this application,which are intended as illustrations of various aspects. Manymodifications and variations may be made without departing from itsspirit and scope, as will be apparent to those skilled in the art. Noelement, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly provided as such. Functionally equivalentmethods and apparatuses within the scope of the disclosure, in additionto those enumerated herein, will be apparent to those skilled in the artfrom the foregoing descriptions. Such modifications and variations areintended to fall within the scope of the appended claims. The presentdisclosure is to be limited only by the terms of the appended claims,along with the full scope of equivalents to which such claims areentitled. It is to be understood that this disclosure is not limited toparticular methods or systems.

The foregoing embodiments are discussed, for simplicity, with regard tothe terminology and structure of infrared capable devices, i.e.,infrared emitters and receivers. However, the embodiments discussed arenot limited to these systems but may be applied to other systems thatuse other forms of electromagnetic waves or non-electromagnetic wavessuch as acoustic waves.

It is also to be understood that the terminology used herein is for thepurpose of describing particular embodiments only, and is not intendedto be limiting. As used herein, the term “video” or the term “imagery”may mean any of a snapshot, single image and/or multiple imagesdisplayed over a time basis. As another example, when referred toherein, the terms “user equipment” and its abbreviation “UE”, the term“remote” and/or the terms “head mounted display” or its abbreviation“HMD” may mean or include (i) a wireless transmit and/or receive unit(WTRU); (ii) any of a number of embodiments of a WTRU; (iii) awireless-capable and/or wired-capable (e.g., tetherable) deviceconfigured with, inter alia, some or all structures and functionality ofa WTRU; (iii) a wireless-capable and/or wired-capable device configuredwith less than all structures and functionality of a WTRU; or (iv) thelike. Details of an example WTRU, which may be representative of anyWTRU recited herein, are provided herein with respect to Figures. 1A-1D.As another example, various disclosed embodiments herein supra and infraare described as utilizing a head mounted display. Those skilled in theart will recognize that a device other than the head mounted display maybe utilized and some or all of the disclosure and various disclosedembodiments can be modified accordingly without undue experimentation.Examples of such other device may include a drone or other deviceconfigured to stream information for providing the adapted realityexperience.

In addition, the methods provided herein may be implemented in acomputer program, software, or firmware incorporated in acomputer-readable medium for execution by a computer or processor.Examples of computer-readable media include electronic signals(transmitted over wired or wireless connections) and computer-readablestorage media. Examples of computer-readable storage media include, butare not limited to, a read only memory (ROM), a random access memory(RAM), a register, cache memory, semiconductor memory devices, magneticmedia such as internal hard disks and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks, and digital versatiledisks (DVDs). A processor in association with software may be used toimplement a radio frequency transceiver for use in a WTRU, UE, terminal,base station, RNC, or any host computer.

Variations of the method, apparatus and system provided above arepossible without departing from the scope of the invention. In view ofthe wide variety of embodiments that can be applied, it should beunderstood that the illustrated embodiments are examples only, andshould not be taken as limiting the scope of the following claims. Forinstance, the embodiments provided herein include handheld devices,which may include or be utilized with any appropriate voltage source,such as a battery and the like, providing any appropriate voltage.

Moreover, in the embodiments provided above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed,” “computer executed”or “CPU executed.”

One of ordinary skill in the art will appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits. Itshould be understood that the embodiments are not limited to theabove-mentioned platforms or CPUs and that other platforms and CPUs maysupport the provided methods.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (RAM)) or non-volatile (e.g., Read-Only Memory(ROM)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It should be understood thatthe embodiments are not limited to the above-mentioned memories and thatother platforms and memories may support the provided methods.

In an illustrative embodiment, any of the operations, processes, etc.described herein may be implemented as computer-readable instructionsstored on a computer-readable medium. The computer-readable instructionsmay be executed by a processor of a mobile unit, a network element,and/or any other computing device.

There is little distinction left between hardware and softwareimplementations of aspects of systems. The use of hardware or softwareis generally (but not always, in that in certain contexts the choicebetween hardware and software may become significant) a design choicerepresenting cost versus efficiency tradeoffs. There may be variousvehicles by which processes and/or systems and/or other technologiesdescribed herein may be effected (e.g., hardware, software, and/orfirmware), and the preferred vehicle may vary with the context in whichthe processes and/or systems and/or other technologies are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a mainly hardware and/or firmwarevehicle. If flexibility is paramount, the implementer may opt for amainly software implementation. Alternatively, the implementer may optfor some combination of hardware, software, and/or firmware.

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beunderstood by those within the art that each function and/or operationwithin such block diagrams, flowcharts, or examples may be implemented,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. In an embodiment,several portions of the subject matter described herein may beimplemented via Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs), digital signal processors (DSPs),and/or other integrated formats. However, those skilled in the art willrecognize that some aspects of the embodiments disclosed herein, inwhole or in part, may be equivalently implemented in integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of skill in the art in light ofthis disclosure. In addition, those skilled in the art will appreciatethat the mechanisms of the subject matter described herein may bedistributed as a program product in a variety of forms, and that anillustrative embodiment of the subject matter described herein appliesregardless of the particular type of signal bearing medium used toactually carry out the distribution. Examples of a signal bearing mediuminclude, but are not limited to, the following: a recordable type mediumsuch as a floppy disk, a hard disk drive, a CD, a DVD, a digital tape, acomputer memory, etc., and a transmission type medium such as a digitaland/or an analog communication medium (e.g., a fiber optic cable, awaveguide, a wired communications link, a wireless communication link,etc.).

Those skilled in the art will recognize that it is common within the artto describe devices and/or processes in the fashion set forth herein,and thereafter use engineering practices to integrate such describeddevices and/or processes into data processing systems. That is, at leasta portion of the devices and/or processes described herein may beintegrated into a data processing system via a reasonable amount ofexperimentation. Those having skill in the art will recognize that atypical data processing system may generally include one or more of asystem unit housing, a video display device, a memory such as volatileand non-volatile memory, processors such as microprocessors and digitalsignal processors, computational entities such as operating systems,drivers, graphical user interfaces, and applications programs, one ormore interaction devices, such as a touch pad or screen, and/or controlsystems including feedback loops and control motors (e.g., feedback forsensing position and/or velocity, control motors for moving and/oradjusting components and/or quantities). A typical data processingsystem may be implemented utilizing any suitable commercially availablecomponents, such as those typically found in datacomputing/communication and/or network computing/communication systems.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely examples, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality may beachieved. Hence, any two components herein combined to achieve aparticular functionality may be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated may also be viewed as being “operably connected”, or“operably coupled”, to each other to achieve the desired functionality,and any two components capable of being so associated may also be viewedas being “operably couplable” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (e.g., bodies of theappended claims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, where only oneitem is intended, the term “single” or similar language may be used. Asan aid to understanding, the following appended claims and/or thedescriptions herein may contain usage of the introductory phrases “atleast one” and “one or more” to introduce claim recitations. However,the use of such phrases should not be construed to imply that theintroduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to embodiments containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should be interpreted to mean “at least one” or “one or more”). Thesame holds true for the use of definite articles used to introduce claimrecitations. In addition, even if a specific number of an introducedclaim recitation is explicitly recited, those skilled in the art willrecognize that such recitation should be interpreted to mean at leastthe recited number (e.g., the bare recitation of “two recitations,”without other modifiers, means at least two recitations, or two or morerecitations). Furthermore, in those instances where a conventionanalogous to “at least one of A, B, and C, etc.” is used, in generalsuch a construction is intended in the sense one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, and C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). In those instances where aconvention analogous to “at least one of A, B, or C, etc.” is used, ingeneral such a construction is intended in the sense one having skill inthe art would understand the convention (e.g., “a system having at leastone of A, B, or C” would include but not be limited to systems that haveA alone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together, etc.). It will be furtherunderstood by those within the art that virtually any disjunctive wordand/or phrase presenting two or more alternative terms, whether in thedescription, claims, or drawings, should be understood to contemplatethe possibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.” Further, the terms“any of” followed by a listing of a plurality of items and/or aplurality of categories of items, as used herein, are intended toinclude “any of,” “any combination of,” “any multiple of,” and/or “anycombination of” multiples of the items and/or the categories of items,individually or in conjunction with other items and/or other categoriesof items. Moreover, as used herein, the term “set” is intended toinclude any number of items, including zero. Additionally, as usedherein, the term “number” is intended to include any number, includingzero. And the term “multiple”, as used herein, is intended to besynonymous with “a plurality”.

In addition, where features or aspects of the disclosure are describedin terms of Markush groups, those skilled in the art will recognize thatthe disclosure is also thereby described in terms of any individualmember or subgroup of members of the Markush group.

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein maybe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the likeincludes the number recited and refers to ranges which can besubsequently broken down into subranges as discussed above. Finally, aswill be understood by one skilled in the art, a range includes eachindividual member. Thus, for example, a group having 1-3 cells refers togroups having 1, 2, or 3 cells. Similarly, a group having 1-5 cellsrefers to groups having 1, 2, 3, 4, or 5 cells, and so forth.

Moreover, the claims should not be read as limited to the provided orderor elements unless stated to that effect. In addition, use of the terms“means for” in any claim is intended to invoke 25 U.S.C. § 112, ¶6 ormeans-plus-function claim format, and any claim without the terms “meansfor” is not so intended.

1.-32. (canceled)
 33. A method implemented by a wirelesstransmit/receive unit (WTRU), the method comprising: receivinginformation indicating a configuration of one or more small datatransmission (SDT) resources; receiving information indicating one ormore data radio bearers (DRBs) which support SDT; receiving informationindicating an inactive radio network temporary identifier (I-RNTI); andafter receiving the indicated I-RNTI and on condition that (1) a size ofUL SDT data present in a buffer of the WTRU is less than a firstthreshold, (2) the UL SDT data present in the buffer is for the one ormore DRBs which support SDT, and (3) a reference signal received power(RSRP) is greater than a second threshold: sending a first transmissionthat includes at least a portion of the UL SDT data present in thebuffer using a configured grant (CG) resource or a random access (RA)resource from among one or more SDT resources.
 34. The method of claim33, wherein the receiving of the information indicating the I-RNTIincludes receiving information indicating a configuration of one or moreCG resources including the CG resource.
 35. The method of any one ofclaim 33, wherein the receiving of the information indicating theconfiguration of the one or more SDT resources includes any ofinformation indicating a configuration of one or more RA resourcesincluding the RA resource, information indicating the first threshold,and/or information indicating the second threshold.
 36. The method ofany one of claim 32, further comprising: receiving informationindicating a timer value associated with SDT, wherein, on condition thata first time period associated with the timer value has not expired, thesending of the first transmission uses the CG resource.
 37. The methodof any one of claim 33, further comprising: after sending the firsttransmission using the CG resource and on condition that a second timeperiod associated with the first transmission has expired, resending thefirst transmission using one of the one or more SDT resources.
 38. Themethod of any one of claim 33, further comprising: after sending thefirst transmission using the CG resource and on condition that a secondtime period associated with the first transmission has not expired,receiving scheduling information for the WTRU.
 39. The method of any oneof claim 33, further comprising: receiving information indicating atimer value associated with SDT, wherein, on condition that a first timeperiod associated with the timer value has expired, the sending of thefirst transmission is performed using the RA resource.
 40. The method ofclaim 39, wherein the sending of the first transmission includes:sending a preamble using the RA resource; receiving a response messageincluding information indicating an uplink (UL) grant; and sending thefirst transmission that includes the at least the portion of the UL SDTdata present in the buffer via the UL grant.
 41. The method of claim 33,wherein the first transmission includes information indicating theI-RNTI.
 42. A wireless transmit/receive unit (WTRU) comprising: aprocessor and a transceiver which are configured to: receive informationindicating a configuration of one or more small data transmission (SDT)resources, receive information indicating one or more data radio bearers(DRBs) which support SDT, receive information indicating an inactiveradio network temporary identifier (I-RNTI), and after receiving theindicated I-RNTI and on condition that (1) a size of UL SDT data presentin a buffer of the WTRU is less than a first threshold, (2) the UL SDTdata present in the buffer is for the one or more DRBs which supportSDT, and (3) a reference signal received power (RSRP) is greater than asecond threshold: sending a first transmission that includes at least aportion of the UL SDT data present in the buffer using a configuredgrant (CG) resource or a random access (RA) resource from among the oneor more SDT resources.
 43. The WTRU of claim 42, wherein the processorand the transceiver are configured to: receive the informationindicating the I-RNTI which further includes information indicating aconfiguration of one or more resources including the CG resource. 44.The WTRU of claim 42, wherein the information indicating theconfiguration of the one or more SDT resources includes any ofinformation indicating a configuration of one or more RA resourcesincluding the RA resource, information indicating the first threshold,and/or information indicating the second threshold.
 45. The WTRU ofclaim 42, wherein the processor and the transceiver are configured to:receive information indicating a timer value associated with SDT, andwherein the processor and the transceiver are configured to, oncondition that a first time period associated with the timer value hasnot expired, send the first transmission using the CG resource.
 46. TheWTRU of claim 42, wherein the processor and the transceiver areconfigured to: after sending the first transmission using the CGresource and on condition that a second time period associated with thefirst transmission has expired, resending the first transmission usingone of the one or more SDT resources.
 47. The WTRU of claim 42, whereinthe processor and the transceiver are configured to: after sending thefirst transmission and on condition that a second time period associatedwith the first transmission has not expired, receiving schedulinginformation for the WTRU.
 48. The WTRU of claim 42, wherein theprocessor and the transceiver are configured to: receive informationindicating a timer value associated with SDT, and wherein the processorand the transceiver are configured to, on condition that a first timeperiod associated with the timer value has expired, send the firsttransmission using the RA resource.
 49. The WTRU of claim 48, whereinthe processor and the transceiver are configured to send the firsttransmission which includes a preamble and the at least the portion ofthe UL SDT data present in the buffer via RA resource.
 50. The WTRU ofclaim 48, wherein the processor and the transceiver are configured tosend the first transmission which includes to: send a preamble via theRA resource, receive a response message including information indicatingan uplink (UL) grant, and send the first transmission that includes theat least the portion of the UL SDT data present in the buffer via the ULgrant.
 51. The WTRU of claim 48, wherein the first transmission includesinformation indicating the I-RNTI.